<p>Research on entrepreneurial ecosystems has expanded rapidly over the past two decades, generating substantial insights into their constituent elements and associated outcomes. However, the microfoundational mechanisms through which these elements and outcomes interact across levels of analysis remain poorly understood, limiting theoretical progress in the entrepreneurial ecosystems literature. This paper offers a critical examination of existing research on entrepreneurial ecosystems, including early contributions that explicitly adopt a microfoundational perspective. We argue that greater conceptual clarity is needed with respect to system-level properties and, in particular, the distinction between microfoundational elements and causal mechanisms. We emphasize the importance of developing functional microfoundations, understood as the strategic actions and interactions through which ecosystem-level elements and outcomes are generated and sustained. Drawing on illustrative examples and alternative conceptualizations of key constructs, the paper provides guidance for developing robust, mechanism-based theories that advance understanding of the microfoundations of entrepreneurial ecosystems. </p>