Social entrepreneurs carefully navigate and create synergies amongst competing institutional logics (Misangyi, Weaver, & Elms, 2008; Battilana, 2006; Aguilera, Judge, & Terjesen, 2016). They interact with commercial entities to secure access to funds, build supply chains and distribution networks, and develop customer relationships. They are simultaneously embedded in the public sphere and therefore accountable to a wide array of stakeholders with varying demands (Dees, 1998; Mair & Marti, 2006). This study seeks to understand what motivates social entrepreneurs to start ventures and integrates expectancy theory and institutional theory to explain the anteedents of social entrepreneurship (SE). We use institutional theory to identify sociocultural processes through which SE gains legitimacy while drawing up on the expectancy theory provides guidance in selecting measures for each institutional dimension. We pair Scott’s (1995) institutional dimensions-- cognitive, normative, and regulatory-- with the three corresponding components of the expectancy model: expectancy [E], valence [V], and instrumentality [I]). The cognitive pillar relates to the aggregate beliefs regarding the feasibility of starting a social business; the normative dimension reflects the degree to which SE is perceived as culturally desirable; and the regulatory climate determines the likelihood of achieving both social and commercial goals.