The expanded sectoral structure, which adds the quaternary sector to the primary, secondary and tertiary sectors, provides a more factual view of economic changes in countries and regions and allows for a more comprehensive analysis of trends in economic activity and individual sectors. The aim of this paper is, against the background of a comparative analysis, to determine the development of the quaternary sector in the 27 EU countries over the period 1995-2021. The quaternary sector and its share in the sectoral structure of the economy is reflected in current approaches to promoting, in particular, qualitative, endogenous and responsible-sustainable development and is associated with the concept of Society 4.0. The activities included in the quaternary sector are an important source of competitiveness and have implications in today's so accentuated applications of the institutional guidelines of regional development to the practical management and support of the territory. The expanded sectoral structure, which adds the quaternary sector to the primary, secondary and tertiary sectors, provides a more factual view of economic changes in countries and regions and allows for a more comprehensive analysis of trends in economic activity and individual sectors. The aim of this paper is, against the background of a comparative analysis, to determine the development of the quaternary sector in the 27 EU countries over the period 1995-2021. The quaternary sector and its share in the sectoral structure of the economy is reflected in current approaches to promoting, in particular, qualitative, endogenous and responsible-sustainable development and is associated with the concept of Society 4.0. The activities included in the quaternary sector are an important source of competitiveness and have implications in today's so accentuated applications of the institutional guidelines of regional development to the practical management and support of the territory. The expanded sectoral structure, which adds the quaternary sector to the primary, secondary and tertiary sectors, provides a more factual view of economic changes in countries and regions and allows for a more comprehensive analysis of trends in economic activity and individual sectors. The aim of this paper is, against the background of a comparative analysis, to determine the development of the quaternary sector in the 27 EU countries over the period 1995-2021. The quaternary sector and its share in the sectoral structure of the economy is reflected in current approaches to promoting, in particular, qualitative, endogenous and responsible-sustainable development and is associated with the concept of Society 4.0. The activities included in the quaternary sector are an important source of competitiveness and have implications in today's so accentuated applications of the institutional guidelines of regional development to the practical management and support of the territory.