Onshore wind energy projects are traditionally developed by commercial project developers. However, the development of these projects is increasingly encountering problems due to poor social acceptance and legal objections. In addition to commercial project developers, renewable energy cooperatives (REScoops) also develop onshore wind energy projects. These non-commercial entities are driven by local, ecological and egalitarian values and often strive for local ownership. This influences the rules-in-use they apply when planning and developing projects. In this paper, fourteen cases of onshore wind energy project development in the Netherlands are analysed using Elinor Ostrom's Institutional Analysis and Development framework. The objectives are: (1) to investigate how the rules-in-use differ between fourteen selected onshore REScoop wind energy projects and onshore commercial wind energy projects in the Netherlands, (2) to investigate how the project duration and the number of submitted views and appeals differ between these two types of wind energy projects, and (3) to determine to what extent the observed differences in rules-in-use can explain the differences in project duration and the number of views and appeals submitted. The research design involves a stepwise approach, including qualitative within-case analysis, followed by quantitative cross-case statistical analysis. The results show that projects developed by REScoops differ on six out of seven rules, especially pay-off, position, and aggregation rules. For projects with a higher percentage of REScoop ownership, the total duration of project planning and development is shorter, there are fewer submitted views during the permit application process and fewer appeals to the Council of State.