The aim of this study was to determine the effects of positive and negative outcome imagery on golf-putting performance. Players of both high and low ability performed a golf-putting task in three imagery conditions: (a) a positive outcome imagery condition, (b) a negative outcome imagery condition and (c) a no-imagery control condition. The task was conducted in a competitive setting, reducing the possibility of demand characteristics. We found that negative outcome imagery was detrimental to putting performance; however, performance in the positive outcome imagery condition was no better than performance in the control condition. There was also evidence to suggest that outcome imagery operated through the mechanism of confidence, as negative outcome imagery was detrimental to both confidence and performance. The results of the present study suggest that golfers should avoid visualizing negative images, as this could damage both confidence and performance.