How effective is social work? This question is being asked more frequently, and with it, the pressure for justification on professionals and institutions in social work is increasing. But what approaches and criteria can be used to evaluate effectiveness in social work? Christian Bleck examines this issue from a social work scientific perspective, particularly focusing on evaluation research. Using the socially significant area of vocational integration support as an example, he highlights specific paths and methods, providing a stimulus for a social work scientific response to the question of effectiveness.