Previous research has shown that experiential knowledge plays an important role for service user movements and has also discussed ambiguities in the definition of this type of knowledge. This study contributes to clarifying how experiential knowledge is understood within the service user movement. Through semi-structured interviews, it explores how Swedish mental health service user organisations (MHSUOs) and service user entrepreneurs (SUEs) regard the role of experiential knowledge for their endeavours. The study shows that SUEs and MHSUOs view experiential knowledge as complementary to established medical and expert knowledge. Both groups further reflect on the functions of individual and collective dimensions of experiential knowledge. Emotions are important in conveying experiential knowledge, although emotional commitment can be short-lived. The study discusses challenges for SUEs and MHSUOs in developing strategies to manage risks tied to strategic essentialism, and also in maintaining a critical standpoint towards established service providers.