<p>Grit, conceptualized as sustained perseverance and enduring interest toward long-term goals, has received increasing attention as a psychological trait influencing faculty research success. This longitudinal study examined how grit predicts both self-reported and bibliometric indicators of research success in a sample of 167 STEM faculty members from 10 U.S. research institutions. Data were collected over three years through annual surveys, supplemented with publication and citation data from the Web of Science. The results indicated that perseverance of effort predicted bibliometric indicators of research productivity, while consistency of interest was more strongly related to faculty self-perceived success in research activities, publications, and grant applications. Over time, the influence of perseverance weakened and, in some cases, became negative, suggesting that sustained effort may yield diminishing returns when institutional support is limited. In contrast, the consistency of interest remained a stable and positive predictor across all time points. These findings highlight grit as a multidimensional construct whose effects on research success evolve over time, underscoring its significance for faculty development initiatives, institutional support structures, and policies aimed at fostering long-term research engagement and productivity.</p>