Background: Socioeconomic differences in health-related behaviors are a major cause of health inequalities. However, the mechanisms (mediation/moderation) by which socioeconomic status (SES) affects health behavior are a topic of ongoing debate.

Purpose: Current research on SES as moderator of the health cognitions-health behavior relation is inconsistent. Previous studies are limited by diverse operationalizations of SES and health behaviors, demographically narrow samples, and between-person designs addressing within-person processes. This paper presents two studies addressing these shortcomings in a within-person multibehavior framework using hierarchical linear models.

Methods: Two online studies, one cross-sectional and one 4 week longitudinal, assessed 1,005 (Study 1; Amazon MTurk; USA only) and 1,273 participants (Study 2; Prolific; international). Self-reports of multiple SES indicators (education, income, occupation status; ZIP code in Study 1), health cognitions (from the theory of planned behavior), and measures of six health behaviors were taken. Multilevel models with cross-level interactions tested whether the within-person relationships between health cognitions and behaviors differed by between-person SES.

Results: Education significantly moderated intention-behavior and attitude-behavior relationships in both studies, with more educated individuals showing stronger positive relationships. In addition, ZIP-level SES (Study 1) moderated attitude-behavior effects such that these relationships were stronger in participants living in areas with higher SES.

Conclusions: Education appears to be an important resource for the translation of intentions and attitudes into behavior. Other SES indicators showed less consistent effects. This has implications for interventions aiming at increasing intentions to change health behaviors, as some interventions might inadvertently increase health inequalities.