In our modern global surroundings, the issue of economic inequalities and their implications is the focus of scientific debate and economic contemplation on the future sustainable development and growth. Despite a general wellbeing, the majority of the population lives in poverty and quite often all the benefits of economic growth are extremely unequally distributed. Even though the attitude to inequality has changed throughout history, depending on the prevailing ideology and theoretical framework, and there are still some differing standpoints today, most scientists claim that deep inequalities in society infringe the outcome of general balance and jeopardize the economic, social and political stability, which has consequences on economic growth and the entire quality of life in a community. The growing and excessive economic inequality which cannot be ignored any more, is becoming the new global challenge of the modern age. Starting from the importance of this topic and the assumption that the growing economic inequalities are affecting economic growth in the modern world, the research in this paper is focused on the analysis of the interdependence of economic inequalities in the distribution of the household income and economic growth. Furthermore, considering the fact that economic inequality is the consequence of a multitude of factors from the economic, social, institutional, cultural and many other dimensions of social development, this paper also analyzes the causative factors that exacerbated economic inequalities in the researched countries. The purpose and goals of the research are relative to the cognition on the direction of the trend of interdependence of economic inequalities in the distribution of income and economic growth, and to the identification of important causative factors of economic inequality. The set goals of the research are realized by comparing the economic and social development of the researched countries, through the analysis of statistical data on the level and trend of economic inequalities measured with different indicators and the empirical research conducted in two main parts focusing on the testing and proving of the following stated research hypotheses: H1: There is an interdependence of economic inequalities in the distribution of household income and economic growth. H1a: The increase of economic inequalities has a negative impact on economic growth. III H1b: There is a long-term connection between economic inequalities and economic growth. H2: Globalization and technological advancement are important causal factors of economic inequalities. The empirical research is conducted for the period between 1995 and 2015, on examples of twenty-eight countries of the European Union (EU-28), marked by a conspicuous diversity in terms of economic and social development, standard of living and quality of life, which leaves consequences on the stability and prosperity of the European Union. Considering the strong heterogeneity of development, which makes it impossible to put all the researched countries in the same panel model, for the needs of this research the EU countries were grouped in four clusters (K1, K2, K3 and K4) using a k-means cluster analysis. Grouping was made according to the criterion of similarity regarding the following six indicators of economic and social development: (1) economic success expressed through the height of the realized real GDP per capita, (2) economic dynamics expressed through the real GDP growth rate, (3) the effectiveness of the labour market expressed through the employment rate, (4) economic inequality in the distribution of household income expressed with the Gini coefficient, (5) at-risk-of-poverty or social exclusion rate and (6) material deprivation rate. In keeping with the conducted cluster analysis, the K1 cluster includes the most developed EU countries having an above average economic growth and a below average level of economic inequalities. The K2 cluster is made up of only one country with a high standard of living, Luxembourg, which was put into a separate cluster due to its peculiarities, mainly the height of its GDP per capita. The K3 cluster mainly includes the Mediterranean EU countries which are not the most developed EU countries according to the analysed indicators but rather average with lower results than K1 cluster countries, and on average better than the K4 cluster countries. The K4 cluster includes most Central European and Baltic countries which are on average on the lowest level of economic and social development in the European Union. These are countries that used to have the so-called planned economy, which went through numerous structural changes in the 1990s affecting their growth and development. The K4 cluster includes Croatia which does not have an enviable position in terms of economic and social development indicators. The first part of the empirical study, directed to the analysis of the interdependence of economic inequalities, measured by means of the Gini coefficient of the equivalent available household IV income and economic growth measured by means of the real GDP, tested and confirmed the first research hypothesis. The empirical research conducted in order to prove the first research hypothesis includes four parts of the analysis, namely: (1) individual regression analysis of the researched countries, (2) panel regression analysis of the countries grouped in clusters, (3) panel and cointegration analysis and (4) cointegration analysis of the EU founder countries. Research on individual regressions for EU countries confirmed that it is not possible to reach a general conclusion on the interdependence of economic inequalities and economic growth on the basis a single regression analysis of the researched countries. However, it can be concluded that the lower the level of economic and social development of single countries, the more negative the trend will be in the interrelationship of economic inequalities and economic growth and vice versa. On the basis the said conclusions, further research was done based on panel data for EU countries (EU-28), grouped into clusters K1, K2, K3 and K4. Despite the differences between EU-28 countries, grouped in clusters, empirical research has shown certain similarities in trends of the analyzed economic variables, which can lead to the conclusion that there are certain common features typical in all researched clusters that can serve as grounds for fundamental conclusions. Common to all clusters are the research results showing that economic inequalities have a negative impact on economic growth trends, only the strength of the effect differs among the clusters. It is lowest in K1 cluster countries, that is, the most developed EU countries, while it is the highest in less developed K4 cluster countries. After it was established on the grounds of a panel regression analysis that there is a negative interdependence between economic inequalities and economic growth in almost all obtained research results, further research tried to establish whether the said interdependence has a long-term character, that is, whether there is a long-term connection between the research variables. Using a panel cointegration analysis, on the basis of formulated panel VECM models, it was established that in the research period (1995-2015) in all analysed clusters (K1, K3, K4) there is a long-term connection between economic growth and economic inequalities, but there are differences in the strength of the connection and the speed of adaptability of the variables to a long-term connection. The K4 cluster countries stand out according to the strength of the long-term connection, therefore, in less developed countries there is a stronger long-term interdependence between economic inequalities and economic growth. V Further empirical analysis was done on examples of EU founder countries, with a special dedication in the research of this paper, since these countries are important starters of economic growth and advancement of the European Union and have an important impact on economic and social trends in other parts of Europe. An empirical analysis and an econometric cointegration approach found a long-term interdependence between economic inequalities and economic growth in all EU founder countries, except the Netherlands. It can thus be concluded that even in the oldest EU member states and countries with a high living standard, an excessive level of economic inequality in society can jeopardize economic growth. The results of the empirical analysis show that the first basic research hypothesis and its side hypotheses may be accepted. We can conclude that there is an interdependence between economic inequalities in the household income distribution and economic growth, which is negative and has a long-term character. Research shows that economic inequalities have a negative effect on economic trends (real GDP) and economic growth potentials. For that reason we need to prevent a further increase of inequality in society. Furthermore, at the level of the European Union (EU-28), observing the average of all clusters, we can conclude that in the research period (1995-2015) there is a growing trend of economic inequalities and that the tenth (highest) decile, that is the share of income belonging to the top 10% of people with the highest income, dominates in the distribution of the available equivalent household income and this is one of the causes for the growth of inequality. In the second part of the empirical research in this paper, relative to the analysis of the causal factors of economic inequalities measured with a Gini coefficient, on the basis the panel regression analysis we tested the second basic hypothesis. In the analysis we started from the assumption that globalization and the closely connected technological advancement beginning in the most developed countries of the world and spilling over into all other economies by means of international exchange and the process of globalization, were important factors of economic inequalities. The empirical analysis found that the second basic hypothesis may be accepted only partially. The hypothesis stating that the degree of globalization is an important causal factor of economic inequalities, in the case when it is expressed through the KOF globalization index, was confirmed only in the K4 cluster, that is, among less developed EU countries. In the example of the cluster K1 which includes highly developed countries, we can draw the opposite conclusion, that is, that the increase of the level of globalization expressed with a KOF globalization index, leads to a decrease of economic inequalities. The second assumption that the degree of technological advancement is an important causal factor of economic inequalities VI can be confirmed only partially, in the example of highly developed countries, meaning clusters K1 and K2. Economic inequality is the consequence of numerous factors arising from the economic, social, institutional, cultural and many other dimensions of social development. Based on this research, we can conclude that there are no univocal causal factors of economic inequalities. Factors differ between the analysed clusters and depend on the level of economic and social development of a certain group of countries. The prevailing causal factors in the most developed countries stem from the degree of technological advancement and the implementation of social policy, meaning that a higher degree of technological advancement increases economic inequality while an increase in social contributions decreases it. Less developed countries are defined by causal factors arising from the level of globalization, labour market and fiscal policy, that is, a higher level of globalization, higher unemployment and higher income tax rates will increase economic inequality. In spite of that, in almost all analysed clusters, what stands out is the effect of the increase of the rate of income gained by the 10% of the wealthiest in the income distribution, the so-called tenth decile, on the growth of economic inequalities. Out of all analysed inequality factors (level of globalization, technological advancement, social welfare cost per capita, income tax rate, unemployment rate and real GDP) the effect of the share of income at the top of the income distribution scale is the most prominent. This can lead to the conclusion that the increase of the share of the tenth decile is, in the majority of the EU countries, an important factor in the economic inequalities trend, meaning that the growth of inequalities is largely the consequence of change in the upper part of income distribution. Considering the fact that the statistical image of economic inequalities among EU countries points to growing and rather felt inequalities which, according to the research results, have a negative impact on economic growth, it is necessary to undertake certain measures so as to alleviate inequalities and turn around the trends towards their decrease. There is no simple and fast solution to the problem of growing economic inequalities since this is a complex phenomenon that is the consequence of numerous factors and the environment we live in. However, it is necessary to develop new concepts in order to decrease the inequality in the future. The guidelines for the decrease of inequality are mainly directed towards the policy of public finances and the redistribution of income and increasingly also to investments in education and skills development, which is becoming a key instrument of the policy for a long-term decrease of inequality and the promotion of equal opportunities. VII Modern cognitions point out that the key factor of economic growth is human capital which is becoming the most important source of competitive advantage. Therefore, everybody should be offered the same opportunities for a successful life because everybody’s potential is valuable and contributes to the whole community. It is also pointed out that social cohesion is becoming a new value in the research of the quality of living, also appearing as a concept in the new paradigm of a smart, sustainable and inclusive growth and development of the European Union. However, despite the proclaimed goals of the creation of a common space of solidarity, prosperity and equal rights and opportunities for all citizens, the European Union is still fractured by sharp inequalities in income distribution, quality of life, access to education, employment opportunities and access to healthcare and other social welfare services. It is becoming increasingly clear that without achieving a higher level of economic equality and social justice in society, enabling all individuals in a community to realize their full potential (human resources), it will not be possible to realize the ever more demanding goals of modern economy, exposed to a growingly stronger and more complex international competition. With this in mind, there is ample room at the level of the European Union for further development and the implementation of strategies directed to an inclusive economic growth and development. In today’s global surrounding conditions in which economic inequalities are becoming one of the most important global challenges, there should be no conflict of what used to be opposing goals: the achievement of a higher level of equality in society and economic growth. In the 21st century global economy, economic equality and the efficiency of the economy are not conflicting categories, quite the contrary, we can conclude that sharp and growing economic inequalities result in a poor efficiency of the economy and a slowdown of economic growth. The research results also support this conclusion indicating that growing economic inequalities in income distribution result in a decrease of economic activity, expressed through real GDP, at which this impact is felt most in less developed European countries. It follows that without achieving a higher level of economic equality in society, it shall not be possible to realize a long-term economic growth and competitiveness on the global market. Today we cannot continue speaking of a socio-economic compromise between equality and growth because these two goals should complement each other within a well-planned sustainable economic and social policy.