Background: The Attitudes Toward Persons with Obesity (ATOP) scale is widely used to assess stigmatization toward persons with obesity. The measure has previously been suggested to assess three facets—self-esteem, personality, and social difficulties—however, psychometric support for this has been inconsistent and warrants further study if the measure intends to be scored this way.Objectives: Explore and confirm the factor structure of the ATOP in people assessed prior to bariatric surgery and reassessed 1 year postoperativelySetting: Midwestern hospital in the USA.Materials and Methods: Three-hundred sixteen people who were seeking bariatric surgery were assessed preoperatively, and 161 of those people were reassessed 1 year after surgery with a battery of measures including the ATOP. Exploratory factor analysis (EFA) was performed on ATOP data from a random split-half of people before surgery, and confirmatory factor analysis (CFA) was performed on the second randomly selected half. With the postoperative sample, a CFA was performed, testing the best-fitting model from the preoperative CFA findings.Results: The EFA suggested a two-factor structure interpreted as self-esteem and personality/social difficulties. This structure was supported by CFA performed on the second randomly selected half of people at preoperative assessment and by CFA performed on people 1 year following surgery. Tests of measurement invariance suggested that the two-factor structure was similar at both time points.Conclusions: Only two factors for the ATOP were empirically supported in the current sample (self-esteem and personality/social difficulties), which is slightly different from the three factors that were originally proposed when the measure was developed. This factor structure is supported both prior to bariatric surgery and 1 year after bariatric surgery.Graphical abstract: