Most European integration theories have perceived the Commission as a unitary actor with a pro-integration agenda.Yet, empirical studies have shown that Commission actors harbor contending views about European governance. These findings raise a theoretical problem for European integration models, and an analytical puzzle for elite studies. European integration theories claiming an independent impact of the Commission on European decision making, need to disaggregate Commission motivations, which is the central purpose of this article. Consistent with recent elite studies, I employ an institutionalist lens to analyze how rules may impact orientations, but I refine the lens to assess institutional socialization and choice in multi-layered institutional settings. I formulate six hypotheses about the interplay between three settings relevant to top Commission officials: Commission, multi-level governance, European public space. Analytically, Commission officials appear reasoned individuals capable of selecting incentives rather than passive subjects of socialization. Evidence comes from 130 interviews and 80 questionnaires, collected in 1995/6 from A1-2 officials, analyzed through interpretative and quantitative analysis. I find that Commission officials constitute a special microcosm of the European public space: less nationalist than most citizens, but divided on the mix of intergovernmental and supranational architectural principles; center-left of the average political actor, but disagreeing on the desirable mix of market and state, opportunity and equity.