Scholars have paid extensive attention to the nature of entrepreneurial founding teams. The focus has largely been on the consequences of founding team composition on factors such as firm growth (Eisenhardt & Schnooven, 1990), mortality (Swaminathan, 1996), the ability to raise equity financing (Beckman et al., 2007), and firm exit (Beckman et al., 2007; Zimmerman, 2008). However, theory on antecedents of founding teams is relatively scant (Forbes et al., 2006). The research that does exist predominantly uses a network lens. For example, scholars have studied the nature of existing network ties, member preferences for homophily, and social capital on the composition of founding teams (Ruef et al., 2003; Aldrich & Kim, 2007). We extend this stream of research by proposing a macro-level explanation of founding team composition. By merging micro-data from the Kauffman Firm Survey (KFS) and the General Social Survey (GSS), we investigate how regional differences human capital and socio-cultural attitudes towards collaboration might together impact the composition of founding teams.