During the last ten years, a revival of the debate concerning the body of knowledge can be observed. During the same period, evidence-based practice caused a lot of resistance inside the social work profession. In this paper, we develop a broad view on evidence-based practice based on the discipline of evaluation research which acknowledges the complexity of the concept of effectiveness. In such a broad view, the first step is to develop and to describe the program theory of social interventions, which consists of the theory of action and the theory of change. We propose two methods to describe social interventions. In addition, we describe three modes to take into account the complexity of social interventions: (1) viable validity, (2) describing the interaction between the social intervention and the social context and (3) a multi-stakeholder approach paying special attention to the "silent voices". [ABSTRACT FROM AUTHOR]