Objectives The purposes of the present studies were to (a) examine the factor structure of sluggish cognitive tempo (SCT) and attention‐deficit/hyperactivity disorder (ADHD) in college students and (b) examine the associations between SCT and academic functioning and internalizing symptoms in college students with and without ADHD. Method In Study 1, a confirmatory factor analysis of the Barkley Adult ADHD Rating Scale‐IV (BAARS‐IV) was conducted in a sample of 768 college students (aged 17–34 years, 68% female). In Study 2, we examined the relation of SCT to academic functioning and internalizing symptoms in a sample of 72 college students rigorously diagnosed with ADHD (aged 17–35 years, 44% female). Results Study 1 results supported the factor structure of the BAARS‐IV, with the optimal model comprising 4 correlated but distinct factors: SCT, Inattention, Hyperactivity, and Impulsivity. After controlling for correlated demographic variables and ADHD symptoms, SCT was significantly related to academic impairment (including grade point average), anxiety, and depression. In Study 2, SCT again contributed unique variance to internalizing symptoms and academic impairment after controlling for correlated participant characteristics (i.e., sex, age, race, parent education level, family income, ADHD medication use, and mental health service utilization) and ADHD symptom severity. Conclusions These results fill an important gap in the literature by (a) confirming SCT to be distinct from ADHD in emerging adulthood, (b) demonstrating SCT to be strongly linked to college student adjustment, and (c) providing support for the hypothesis that SCT is associated with psychosocial functioning in both individuals with and without ADHD.