This chapter synthesizes the main theoretical and empirical developments surrounding the relationship between ESG analysis and corporate performance, both financial and extra-financial. Building on the historical and regulatory foundations outlined in previous chapters, it explores how organizations integrate ESG concerns into their strategic and reporting frameworks in response to growing societal expectations and stakeholder pressures. The first section provides a theoretical lens for understanding ESG dynamics, drawing from legitimacy, stakeholder, and signaling theories. These frameworks explain how firms engage in ESG reporting to gain social legitimacy, respond to stakeholder demands, and signal responsible behavior in markets characterized by information asymmetries. The second section reviews empirical evidence on the relationship between ESG performance and financial outcomes. While some studies suggest ESG practices can enhance firm value through reputation, efficiency, and innovation, others find mixed or even negative effects, particularly for SMEs. Factors such as industry sector, firm size, and the nature of ESG activities influence outcomes. The chapter also details how ESG impacts valuation, including product-market perception, risk reduction, cost of capital, and consumer behavior. Finally, the chapter highlights critical limitations in ESG research, notably the lack of focus on SMEs and VSEs, whose limited resources and reporting capacities challenge ESG integration.