We explored the relationships between sociocultural and psychological constructs and adherence to antiretroviral therapy among predominantly Spanish-speaking immigrant Latinos in the southeastern United States. A cross-sectional clinic-based sample of immigrant Latino men and women participated in an interviewer-administered assessment. Self-reported prevalence of adherence was assessed along with demographic characteristics, acculturation, physician trust, social support, and theory of planned behavior (TPB) constructs: attitude, subjective norm (SN), and perceived behavioral control (PBC). A total of 66 respondents met inclusion criteria. Average age was 38 years old, 74% of respondents were male, 71% heterosexual, and 86% reported being from Mexico or Central America. Prevalence of "complete" adherence (i.e., not missing a single dose) in the past 30 days was 71%. Social support was significantly and inversely associated with adherence, PBC, and attitude. Positive correlates of adherence included attitude, PBC, and employment status. In multivariable analysis, SN and PBC were significantly associated with social support, controlling for acculturation, physician trust, and number of behavioral referents. TPB constructs have utility in explaining ART adherence among immigrant Latinos in the "Deep South." Further research is necessary to understand the complex relationships between social support, attribution processes, and ART adherence outcomes.