In recent times, small and medium-sized companies (SMEs) have focused their activities on short-term financial results. Corporate social responsibility (CSR) is among the organizational practices currently being adopted by companies to increase their competitiveness. While some companies implement CSR out of curiosity or because it is aligned with their true social vocation, most embrace it to increase economic and financial performance. Whereas some theories support CSR practices and assert the great benefits these activities can yield, other theories state that management should not allocate resources to CSR actions. Focusing on SMEs, the present study sought to examine the effects of CSR on profitability from three perspectives: the social, the environmental, and the economic dimensions of social responsibility. The sample for this study included 81 companies in the industrial (54.3%) and services (45.7%) sectors operating in the south of the state of Sonora (Mexico). Data collection was carried out from August to November, 2013, and used a self-directed survey administered to company managers. Results were analyzed and validated using a variance-based statistical technique focused on structural equation models (SEM); the structured relationships were validated by partial least square (PLS) modeling using the SmartPLS Professional software (version 3.2.6). Our findings provide evidence that social and economic CSR activities have a positive influence on profitability in SMEs. This study contributes to the development of the main literature on CSR practices in their social, environmental, and economic dimensions: firm theory, sustainability theory, and stakeholder theory.