This tutorial explores action research as a method for investigating information systems. Action research is a research method used in the social and medical sciences since the mid-20th century and has become increasingly important in information systems research in the late 1990s. It is rooted in post-positivist philosophy, emphasizing idiographic and interpretive research ideals. Action research has a history in information systems that can be linked to early work by Lewin and the Tavistock Institute. It varies in form and is suited to different problem domains. The most common form is a participatory method based on a five-step model, exemplified by published information systems research. Action research is a collaborative process that involves researchers and subjects as co-participants in the research and change experiences. It is grounded in practical action aimed at solving immediate problem situations while informing theory. The method is characterized by an interpretivist viewpoint, an idiographic viewpoint, and the use of qualitative data and analyses. Action research is closely related to consulting and is used to study complex social processes by introducing changes and observing their effects. The paper outlines the history, context, and domains of action research in information systems. It describes the method and provides details about a published example. The paper emphasizes the participatory form of action research. It is organized into six sections, covering the scientific and philosophical context, the method, a "how-to" guide for conducting action research, a case study of a published action research project, and the limitations of the approach. Action research is particularly useful for understanding change processes in social systems. It is applied in settings where the research and client goals align, and where a theoretical framework is established. The method is effective in settings where the research is a cyclical process linking theory and practice. It is used to study new or changed systems development methodologies, which inherently involve intervention. Action research differs from consulting in several key ways, including motivation, commitment, approach, foundation for recommendations, and the essence of organizational understanding. Action research is motivated by scientific interest, while consulting is motivated by commercial benefits. Action research involves collaboration and is based on practical success from iterative experimental changes, while consulting is based on independent critical analysis of the problem situation. The action research approach is a five-phase, cyclical process that includes diagnosing, action planning, action taking, evaluating, and specifying learning. Each phase is reviewed in detail. The process involves establishing a client-system infrastructure, diagnosing the problem, planning actions, taking action, evaluating the outcomes, and specifying learning. The method is particularly effective in participatory action research, where client participants are engaged in the research process. Action research has several limitations, including the difficulty of applying it in an orchestrated research program and the potential for researchers to lose contact with their obligations to develop general knowledge about related theories. Despite these challenges, action research is a valuable method for information systems research, providing a rewarding experience for researchers who want to work closely with the practitionerThis tutorial explores action research as a method for investigating information systems. Action research is a research method used in the social and medical sciences since the mid-20th century and has become increasingly important in information systems research in the late 1990s. It is rooted in post-positivist philosophy, emphasizing idiographic and interpretive research ideals. Action research has a history in information systems that can be linked to early work by Lewin and the Tavistock Institute. It varies in form and is suited to different problem domains. The most common form is a participatory method based on a five-step model, exemplified by published information systems research. Action research is a collaborative process that involves researchers and subjects as co-participants in the research and change experiences. It is grounded in practical action aimed at solving immediate problem situations while informing theory. The method is characterized by an interpretivist viewpoint, an idiographic viewpoint, and the use of qualitative data and analyses. Action research is closely related to consulting and is used to study complex social processes by introducing changes and observing their effects. The paper outlines the history, context, and domains of action research in information systems. It describes the method and provides details about a published example. The paper emphasizes the participatory form of action research. It is organized into six sections, covering the scientific and philosophical context, the method, a "how-to" guide for conducting action research, a case study of a published action research project, and the limitations of the approach. Action research is particularly useful for understanding change processes in social systems. It is applied in settings where the research and client goals align, and where a theoretical framework is established. The method is effective in settings where the research is a cyclical process linking theory and practice. It is used to study new or changed systems development methodologies, which inherently involve intervention. Action research differs from consulting in several key ways, including motivation, commitment, approach, foundation for recommendations, and the essence of organizational understanding. Action research is motivated by scientific interest, while consulting is motivated by commercial benefits. Action research involves collaboration and is based on practical success from iterative experimental changes, while consulting is based on independent critical analysis of the problem situation. The action research approach is a five-phase, cyclical process that includes diagnosing, action planning, action taking, evaluating, and specifying learning. Each phase is reviewed in detail. The process involves establishing a client-system infrastructure, diagnosing the problem, planning actions, taking action, evaluating the outcomes, and specifying learning. The method is particularly effective in participatory action research, where client participants are engaged in the research process. Action research has several limitations, including the difficulty of applying it in an orchestrated research program and the potential for researchers to lose contact with their obligations to develop general knowledge about related theories. Despite these challenges, action research is a valuable method for information systems research, providing a rewarding experience for researchers who want to work closely with the practitioner