The article is predominantly theoretical in nature, but includes current examples from business practice. The purpose of the work is to study the nature of social efficiency, which is created during the implementation of service activities. The main provisions of this study are to analyze and generalize modern approaches to the effectiveness of service activities, namely to its social component using traditional methods of scientific knowledge. The scientific novelty of the study lies in the formulation of the basic principles of service activities and the interpretation of their application at various levels, as well as in putting forward the thesis about the dual nature of the social effectiveness of service activities. In the course of studying the principles of service activities, the authors focused attention on the principle of social efficiency, showing the manifestation of the principle of social efficiency at different levels: from the individual to the population of the country. Particular attention is paid to the employment and organization of recreation for people with disabilities. In the second part of the study, corporate social responsibility (CSR) of a service enterprise is considered as a manifestation of its social effectiveness, and the features of the implementation of CSR activities by service enterprises are outlined with specific examples from Russian practice. At the end of the article, a brief review of methods for assessing the impact of CSR on the basic efficiency of an enterprise is carried out, a thesis is formulated about the duality of the social effectiveness of service activities - from the provision of specialized services by service enterprises and from their implementation of corporate social responsibility measures.