The current study clarifies the role of personality for increased gambling behaviors. The authors compared five traits, each involving a different disposition to rash action, predicting increased gambling behavior across the transition into college life. The authors sampled 418 college students (75% female; median age 18.0 years) across their freshman year. Participants completed the UPPS-P scale and measures to assess gambling and risky behavior participation. SEM analyses showed that although the disposition to engage in rash action when in an unusually positive mood (positive urgency), lack of planning, and sensation seeking all related to both gambling behavior and general risky behavior (e.g., mountain climbing) cross-sectionally, only positive urgency predicted longitudinal increases in gambling behavior and only sensation seeking predicted longitudinal increases in general risky behaviors. Beginning college students high in positive urgency are at increased risk to increase their gambling behavior in college.