Fifty years ago, social work understood research as depicted by logical positivism and its successors, and an obsolete scientism still held sway. This paper will briefly trace the history of the epistemological debate that has taken place in social work in the last 30 years, which is directly related to the credibility of agency-based research and of qualitative methods as well as to issues in knowledge development about oppressed groups. Contemporary epistemologies-realism and pragmatism-offer frameworks that are compatible with what is needed for practice-relevant research and knowledge development: firm grounding for methodological pluralism, attention to the social and political nature of science, the embrace of theory, and an end to scientism without resort to relativism. If these changes in epistemological thinking can be fully embraced, the twentyfirst century can be a very productive one for agency-based and practice-relevant social work research.Keywords Social work research Á Epistemology Á Realism Á Pragmatism Á Critical theory Á Practice research Fifty years ago, social work and the social sciences understood research as depicted by logical positivism and its successors. In 1960, what Heinemann (Pieper) (1981 called an obsolete scientism still held sway, discrediting both practice-based research and analytically-informed practice. Since then, social work has grown in the sophistication of its thinking about epistemology, which can legitimate practice-relevant research methods and models for the future. However, greater knowledge of contemporary epistemologies will be needed to strengthen practicerelevant research in the years to come. This paper will briefly trace the history of the epistemological debate that has taken place in social work in the last 30 years, which is important for the credibility of agency-based research and of qualitative methods as well as to issues in knowledge development about oppressed groups. It will outline two contemporary epistemologiesrealism and pragmatism-that can inform and support a range of research methods and innovative approaches to practice-relevant research. Influences from social constructionism and from feminist and post-colonialist analyses will also be briefly discussed since they have influenced contemporary thinking in both realism and pragmatism.To position myself in this task, I am not formally educated in philosophy or epistemology. However as a teacher and practitioner of social work research, I encountered problems with the dominant view of science and research, and I was fortunate to have had a doctoral education that introduced me to epistemological thinking. Feminist critiques of knowledge development were also influential. The views I have developed on these matters come from reading in the field over many years, but they do not do justice to the precise and important debates that take place among philosophers of science. My goal instead is to present the broad outlines of two kinds of current epistemological thinking. However, no reader should ...