In a three-wave, year-long, large-sample dataset (N = 755), 10 candidate "personality strengths" (Grit, Gratitude, Curiosity, Savoring, Control Beliefs, Meaning in Life–Presence, Strengths Use, and Engagement, Pleasure, and Meaning-Based Orientations Toward Happiness) were compared as predictors of 6-month increases in goal attainment, and as moderators of goal attainment effects upon boosted subjective well-being (SWB). Seeking internal replication, we tested our models twice, both during T1-T2 and during T2-T3. We also examined whether any Personality x Attainment moderator effects upon change in SWB at T2 still persisted at T3. Grit was the only candidate strength that predicted increased goal attainment from T1 to T2 and from T2 to T3, and Curiosity was the only candidate strength that moderated attainment effects on well-being from T1 to T2 and from T2 to T3. T2 Goal attainment effects on SWB were best sustained at T3 when Meaning Orientation increased from T1 to T2. Implications for identifying keystone constructs in personality (and positive) psychology are discussed.