This paper is motivated by the intention to contribute to a contextual understanding of projects. More specifically, the analysis starts from the assumption that essential processes of creating and sedimenting knowledge accrue at the interface between projects and the organizations, communities, and networks in and through which projects operate. By adopting such a contextual perspective, the chief aim of the present study is to unfold a conceptual framework for analyzing processes of project-based learning. This conceptual framework is built around the notion of the project ecology. By consecutively disentangling the constitutive layers of project ecologies — the core team, the firm, the epistemic community, and the personal networks — the basic organizational architecture of project ecologies is revealed. This architecture is employed as a theoretical template for an exploration of learning processes in two ecologies which are driven by opposing logics of creating and sedimenting knowledge. In this comparative analysis, the cumulative learning logic of the software ecology in Munich is confronted with the disruptive learning regime in the London advertising ecology.