Assigned participants in the Hypertension Prevention Trial to one of four diets for a period of 3 years: (a) weight loss, (b) reduced sodium, (c) weight loss plus reduced sodium, and (d) reduced sodium plus increased potassium. At 6-month intervals, they reported problems they were having adhering to their diets. Problem attributions were coded along the dimensions of internality, stability, and controllability and were categorized as intrapersonal or extrapersonal. Attributions were found to differ by type of diet and sex of participant. Participants assigned to weight-loss groups were significantly more likely than those assigned to non-weight-loss groups to blame themselves for their problems with adherence, making characterological as opposed to external or situational attributions. Men perceived problems to be more controllable than women. Attributions did not predict weight loss, change in urinary sodium, or change in potassium excretion.