To examine the ability of the personality dimension dispositional optimism to predict short-term obesity treatment outcomes (weeks of program attendance and weight loss), 177 consecutive persons seeking outpatient treatment at a university-based weight management center completed the revised Life Orientation Test (LOT-R; Scheier, Carver, & Bridges, 1994) and underwent a comprehensive medically monitored weight loss program. The overall LOT-R and optimism subscales did not correlate with either attendance or weight loss. However, the pessimism subscale was positively associated with weeks of attendance.