This paper presents two studies that explore proactive problem solving and its antecedents using novel laboratory-based methods. In Study 1, 53 psychology students completed an in-basket task requiring proactive problem solving, with solution proactivity evaluated by judges. Study 2 replicated and extended the study with 167 employees. Both studies explored the role of different forms of motivation, as it has been speculated that only autonomous motivations should contribute to proactive behavior. Study 1 showed that those participants higher in intrinsic motivation were more proactive, while Study 2 showed that those participants higher in controlled motivations were less proactive. Studies showed a consistent difference between autonomous and controlled motivations in their relations with proactivity. Experimental methods appear to be a useful approach to examining factors influencing cognitive aspects of the proactivity process.