Despite the evolution of the grit conceptualization over the years, the psychometric validity of scales and construct structure remain unclear. Consequently, this study aims to provide new evidence that broadens the current understanding of the grit's dimensional nature in the Spanish population by examining the psychometric properties of the Spanish Grit-S Scale. The sample comprised 1027 undergraduates. The average age of the participants was 20.93 years (ranging from 18 to 45 years). The internal structure was analyzed using confirmatory factor analysis, and the reliability was assessed using internal consistency measures and composite reliability. Findings indicated that a bidimensional factor structure (i.e., consistency of interest and perseverance in effort) achieved better fit indexes, while overall grit showed superior reliability. Perseverance in effort was more strongly related to academic performance. The results suggest that measuring grit as a two-dimensional construct is preferable because each dimension accounts for different variances in outcomes. This study may contribute to addressing the controversy surrounding the measurement of this construct and assist researchers and practitioners in evaluating interventions that include grit among their outcomes.