Objective: To describe clinically relevant effects of lisdexamfetamine dimesylate (LDX) on emotional expression (EE) in children with ADHD. Method: Children with ADHD participated in a 7-week, open-label, LDX dose-optimization study. Expression and Emotion Scale for Children (EESC) change scores were analyzed post hoc using two methods to determine proportion of participants with different categories of clinical response based on (a) clinically significant (movement greater than 2 SD from baseline mean)/reliable change (not due to measurement error) and (b) standard error of measurement (SEM) as a measure of clinically meaningful change. Results: With LDX, no participants showed clinically significant/reliable improvement; 0.7% showed clinically significant/reliable deterioration of EE by reliable change index and movement from baseline mean. One third of participants had improved EE by SEM criteria; 9.2% had categorical worsening. Conclusion: Using clinically meaningful change and clinically significant/reliable change categories derived from the EESC, most participants had no worsening of EE with LDX. (Contains 2 tables and 4 figures.)