Healthy diet and physical activity (PA) prevent and reduce chronic disease. Social cognitive theory delineates multiple attitudes and barriers that influence these behaviors. Understanding covariation in these attitudes and barriers is complex. We examined whether individuals could be grouped into a small number of categories that are easier to study. Interviews were conducted with 982 adults from two low-income, predominantly African American neighborhoods in the same city. Social cognitive constructs, including self-efficacy, social norms, and internal and external barriers to diet and exercise, and walking were self-reported. We measured moderate to vigorous physical activity with accelerometers and diet with 24-hour recalls. We conducted a latent profile analysis of attitudes and barriers to diet and PA and identified four classes: (a) "moderate diet and negative exercise attitudes," where participants were roughly average on dietary attitudes but reported exercise-related challenges, including lower social support, outcome expectancies, physical functioning, and self-efficacy; (b) "few barriers and benefits of healthy diet and exercise," where participants reported fewer barriers and lower outcome expectancies for diet and PA; (c) "moderate overall attitudes," where participants had average scores on most indicators but below-average exercise self-efficacy and slightly more exercise barriers; and (d) "positive overall attitudes," characterized by more positive attitudes toward both diet and PA across most domains, particularly regarding self-efficacy to overcome exercise barriers. These profiles could inform efforts to tailor individual-level interventions for diet and PA of persons at high risk of chronic diseases.