The research approach of multi-grounded action research (MGAR) is presented and analyzed. This is based on a review of issues and concerns in information systems action research. MGAR builds on the epistemological principles of multi-grounding. This combines empirical, theoretical and internal grounding. The multi-grounded approach builds on elements from grounded theory; i.e. building theory inductively from data through coding procedures, but it also comprises an abductive use of extant theory. MGAR is described through six knowledge contributions: (1) the MGAR process model, (2) the MGAR knowledge model, (3) the MGAR theory model, (4) the principle of the multi-grounded change outcome, (5) the principle of the multi-grounded theory outcome and (6) the principle of mutuality of purposes. MGAR has been applied in an IT service management (ITSM) case, which serves an illustration and a validation of MGAR. In this MGAR case, the improvement of ITSM has been conducted and studied through a multi-organizational setting. In the case, there was a special focus on the service quality of IT services and the relations between service providers and customers.