<p>Identifying causality in subjective well-being (SWB) is challenging, as it involves both factors that influence SWB and outcomes that it generates. While previous studies explored beliefs about SWB’s causes and the effects of SWB beliefs on behavior and actual SWB, little is known about perceptions of reverse causality—how SWB itself is viewed as a cause — and how beliefs about SWB causality relate to actual outcomes. Understanding these mechanisms could advance research on SWB causality and highlight the potential of beliefs to motivate action and predict SWB. This study investigated perceptions of well-being causality (WB causality) in 13 domains (e.g., financial resources, health) and their role in guiding behavior and predicting SWB. We examined whether the perception that a domain influences WB is associated with greater effort, which in turn predicts higher SWB, and if WB is perceived primarily as a cause or an effect. An online sample of 771 U.S. adults completed measures of bidirectional WB causality perceptions, domain-specific effort, and SWB. Findings revealed that perceptions were associated with SWB through effort, highlighting their possible role in predicting behavior and overall SWB. Believing that life domains influence WB was associated with greater effort, which was linked to better actual SWB. Perceptions of WB as a cause rather than an effect varied across domains. These results underscore the significance of how SWB is perceived and the implications for societies and organizations, which could leverage perceptions to promote desired behaviors and enhance SWB. Thus, this study contributes to the growing literature on beliefs about SWB and causal dynamics.</p>