In many of today's enterprises, data management and data quality are poor. Over the last few years, a new solution strategy has emerged, known as data governance: an overarching methodology that defines who is responsible for what data at what point in a business process. Although positive effects on the business performance and compliance of enterprises are seen in practice, a substantiated method for determining the effects of data governance has not yet been developed. This paper reports on explorative research to develop such a specification method. Through a conceptualization of data governance based on literature, case study analysis of clients of a large consultancy firm and interviews with representatives of companies that have recently implemented data governance, an effect specification framework was developed. Using the interviews, initial steps towards validation were performed.