Research addressing the microfoundations of corporate social performance (CSP) in small and medium-sized enterprises (SMEs) remains sparse. This paper aims to investigate how SME managers' ethical ideology affects CSP and examines the mediating role of their CSR orientation (CSRO): economic, legal, ethical, and philanthropic. Data were collected from 239 SME managers in the United Kingdom via survey and analyzed using regression and structural equation modeling. Findings show that idealism positively affects CSP, with philanthropic CSRO partially mediating this relationship. It also positively impacts all CSRO types. Relativism does not influence CSP but positively relates to economic CSRO. This paper is the first to integrate idealism, relativism, multiple CSRO types, and CSP into a unified model, providing insights into their interactions. It expands knowledge of CSP's personal drivers and offers guidance for educators, policymakers, and managers seeking to foster CSP.