Achievement flow involves total absorption in an activity, high concentration without effort and merging of thought and action. The authors propose that achievement flow is facilitated by dynamic alternatives between low positive affect (“seeing difficulty”) and high positive affect (“mastering difficulty”). Consistent with this hypothesis, three studies showed that traits associated with reduced positive affect (avoidant adult attachment, schizoid-like personality style, introversion) and traits supportive of restoring positive affect (mastery orientation) predicted achievement flow, as assessed with a new operant motive (...) test (OMT). Achievement flow motives were further found to be associated with flow experiences in achievement tasks (Study 1), intrinsic motivation in an academic context (Study 2), and volitional facilitation as assessed by removal of Stroop interference after experimentally induced difficulty and positive affect (Study 3). These findings offer converging evidence that flow experiences arise from dynamic changes in positive affect. (shrink)