The paper aims to analyze the mechanisms whereby immigrant entrepreneurship emerges and develops. In this connection, we argue that studies of immigrant entrepreneurship can benefit from deeper dialog with economic sociology. With the idea of mixed embeddedness as our starting point, we advocate an analytical framework of the generative mechanisms of immigrant entrepreneurship that traces the interconnections between the approaches of New Economic Sociology, Political Economy and Neo-Institutionalism from the perspective of mechanismbased explanation. This framework is then applied to a qualitative case study conducted on two micro immigrant-entrepreneur groups: the Italian ice cream parlor owners and pizzeria owners in Frankfurt am Main, Germany, selected inasmuch as they represent polar forms of immigrant entrepreneurship. In this perspective, empirical findings show detailed differences between the two groups. For pizzeria owners, entrepreneurial transition is the result of a short-term project, the actors are part of small networks, do business in predominantly local markets, and are mainly shaped by mimetic isomorphism. By contrast, the ice cream parlor owners script more consistent entrepreneurial paths, belong to more highly articulated networks, show specific aspects of economic transnationalism, and structure themselves by a predominately normative process.