The study of short-term projects in policy implementation has lately gained ground among scholars of environmental governance and public administration. The increasing reliance on and prevalence of projects, or 'projectification', has spurred critical debates on the ability of projects to contribute to long-term goals, including sustainability, as well as institutional change. Yet, the literature on projectification lacks specificity in terms of how projects are understood, how the relationship between projects and permanent organizations looks like, and how projects can influence institutional orders. The aim of this paper is to systematize the literature in order to uncover the processes of transforming project outputs into institutional change. Three models of projectified governance - mechanistic, organic, and adaptive - is presented, providing a conceptual apparatus that advances the study of projects in environmental policy and governance. The paper argues that the adaptive model, with its reliance on multi-scalar networks for the coordination of project activities and knowledge, shows most promise in achieving institutional change to address complex environmental problems.