This study examines how middle managers support their employees' strengths use via three sequential analyses. In Study 1, an open-ended questionnaire survey of high-performing middle managers at a global manufacturer in Japan (n = 144) was conducted to collect comments on strengths use support (SUS). The grounded theory approach was used to generate four categories of SUS, and a quantitative questionnaire was developed based on the analysis. In Study 2, three dimensions of SUS (understanding employees' strengths and interests, developing strengths through challenging assignments, and supporting the accomplishment) were identified by exploratory factor analyses using the questionnaire survey data of middle managers in Japanese firms (n = 208). Study 3 examined the validity and reliability of the three-dimensional model using confirmatory factor analysis of the questionnaire survey data of middle managers in Japanese firms (n = 209).