Maximizing the translation of ability into accomplishment is of considerable interest. A two-factor construct of “grit” as perseverance and consistency of interest has been argued to predict accomplishment over and above personality and IQ (Duckworth, Peterson, Matthews, & Kelly, 2007). Here we test this in linked analyses addressing the structure of Grit and its fit within broader personality and intelligence constructs. An initial Structural Equation Model (SEM) in 494 subjects (age 18–69 years) confirmed a two-factor structure of the Grit scales. Tests adding facet-level assessments of conscientiousness (C) and neuroticism (N) indicated that while grit consistency fit well under C, grit perseverance and related measures of control defined an “effortful persistence” construct which could not be reduced to effects of C and/or N. While conscientiousness and IQ adequately accounted for school grades, higher perseverance was associated with higher life-course accomplishment. The work supports three factors of central relevance to achievement: IQ, conscientiousness, and effortful persistence, each with distinct mechanisms.