Policy design has returned as a central topic in public policy research. An important area of policy design study deals with effectively attaining desired policy outcomes by aligning goals and means to achieve policy design fit. So far, only a few empirical studies have explored the relationship between policy design fit and effectiveness. In this paper, we adopt the multilevel framework for policy design to determine which conditions of policy design fit—i.e., goal coherence, means consistency, and congruence of goals and means across policy levels—are necessary and/or sufficient for policy design effectiveness in the context of policy integration. To this end, we performed a qualitative comparative analysis of Dutch regional transport planning including all twelve provinces. Outcomes show no condition is necessary and two combinations of conditions are sufficient for effectiveness. The first sufficient combination confirms what the literature suggests, namely that policy design fit results in policy design effectiveness. The second indicates that the combination goal incoherence and incongruence of goals and means is sufficient for policy design effectiveness. An in-depth interpretation of this counterintuitive result leads to the conclusion that for achieving policy integration the supportive relationship between policy design fit and policy design effectiveness is less straightforward as theory suggests. Instead, results indicate there are varying degrees of coherence, consistency, and congruence that affect effectiveness in different ways. Furthermore, outcomes reveal that under specific circumstances a policy design may be effective in promoting desired policy integration even if it is incoherent, inconsistent, and/or incongruent.