Research on the importance of complete mental health has led to increased focus on students' subjective well-being (i.e., happiness and life satisfaction) coupled with the traditional attention to psychopathology. Although screeners for psychopathology abound, the present project is novel in applying best practices in universal screening to grade level-wide assessment of children's life satisfaction, followed by implementation of a positive psychology intervention for students identified through the screener. In this case study of 375 third- to fifth-grade students in one elementary school, 93.6% participated in the screening, 11.2% qualified for supplemental services based on screening cutoff scores, and 4.8% took part in the targeted intervention to improve subjective well-being. Repeated measures analysis of mean scores revealed the intervention increased children's life satisfaction, lending support for the value of universal screeners in the process of service delivery. Implications for practice regarding universal screening and intervention for life satisfaction are discussed.