Low enrollment in behavioral weight loss treatments limits their impact. We aimed to identify factors associated with treatment initiation. The participants were outpatients (n = 198) at Veterans Affairs (VA) healthcare facilities who were referred to a free VA-based behavioral weight loss treatment. Participants were assessed on psychosocial factors potentially relevant to treatment initiation. Subsequent treatment initiation was determined via medical record review. Study participants were 77 % male, 60 % African American, and 54 % initiated treatment. In multivariable analyses, treatment initiation was associated with being single, higher anxiety, and patients' perceptions that referring provider supported their weight autonomy. Endorsement of treatment barriers was not associated with treatment initiation. Treatments offering in-person sessions and mood management components were rated as more preferred. Initiation of behavioral weight loss treatments may increase if patients believe that providers respect their weight control autonomy and if healthcare organizations offer treatments that match patients' preferences.