This article details the development and preliminary validation of a multidimensional self-report measure of emotion for 8- to 12-year-old children--the How I Feel (HIF). Item generation and selection occurred via 2 pilot administrations (ns = 250 and 378, respectively). Ten experts provided data on content validity. Exploratory factor analysis and subsequent confirmatory factor analysis with samples of 406, 524, 349, and 349 3rd-through 6th-grade children supported a 3-factor model, including the frequency and intensity of (a) positive emotion, (b) negative emotion, and (c) positive and negative emotion control. Results showed moderate longitudinal stability for 120 children over 2 years. Concurrent validity was established. The HIF can be useful in understanding the interplay between arousal and control in social-emotional adjustment in school-age children.