OBJECTIVES:   In adults with executive dysfunction and mild major depressive disorder (MDD), lisdexamfetamine dimesylate (LDX) augmentation significantly improved executive dysfunction (primary endpoint) on the Behavior Rating Inventory of Executive Function–Adult Version (BRIEF-A). Because cognitive impairment can affect functioning, including the ability to work, we describe LDX effects on functional outcomes from the aforementioned study. METHODS:   This double-blind, placebo-controlled study enrolled participants (18–55 y) with mild MDD (Montgomery-Åsberg Depression Rating Scale total score ≤18) and executive dysfunction (BRIEF-A Global Executive Composite T-score ≥60) on stable SSRI monotherapy for ≥8 weeks. After 2 weeks of screening, participants were randomized to 9 weeks of double-blind LDX (week 1: 20 mg/d; weeks 2–6: maintain or increase LDX in 10-mg increments weekly to 70 mg/d; weeks 7–9: maintain optimized dose) or placebo augmentation, followed by 2 weeks of single-blind placebo. Prespecified secondary functional endpoints included the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) and Endicott Work Productivity Scale (EWPS). Analyses included analysis of covariance in randomized participants who took ≥1 study drug dose and had ≥1 postbaseline BRIEF-A assessment. RESULTS:   Of 143 randomized participants (placebo, 72; LDX, 71), 119 completed double-blind treatment (placebo, 59; LDX, 60). For the Q-LES-Q, least squares (LS) mean (95% CI) treatment differences at endpoint significantly favored LDX in 5 of 10 domains: “physical health activities” (9.6 [3.6, 15.6]; P=0.0020), “feelings” (5.8 [0.0, 11.6]; P=0.0481), “work” (9.1 [2.0, 16.1]; P=0.0123), “household duties” (8.8 [2.2, 15.4]; P=0.0094), and “general activities” (6.2 [1.0, 11.4]; P=0.0191); no differentiation was observed in the other domains. For the EWPS, the LS mean (95% CI) treatment difference at endpoint numerically favored LDX but was not statistically significant (–4.4 [–10.9, 2.0; P=0.1731).   CONCLUSIONS: These findings suggest LDX augmentation modestly improves functional outcomes in adults with partially or fully remitted MDD.