Scholars have paid considerable attention to studying the relationship between corporate social responsibility (CSR) and firm performance. Yet, little empirical research demonstrates what actually shapes or drives CSR. This paper builds a case that formal strategic planning is one such driver in that it creates awareness of and formulates responses to stakeholder demands for CSR. However, exploring single variable relationships is problematic, as other important endogenous factors need to be considered in explaining CSR. Specifically, firm culture is identified as influencing a firm's orientation towards the responsible treatment of stakeholders. One such cultural factor, humanistic culture, is argued to have a positive effect on CSR. By studying a sample of heterogeneous firms in Australia, results demonstrate that a formal strategic planning effort is positively linked to CSR. Further, a humanistic culture positively impacts CSR, after accounting for a firm's formal planning efforts.