Using their strengths and virtues enables individuals to build resilience and alleviate mental health issues. However, most existing instruments for measuring strengths are too lengthy to provide effective assessment for clinical screening. A brief instrument with good factorial and ecological validity is needed to measure strengths, especially among individuals with mental health issues. In this study, the authors developed a brief inventory, the Brief Strengths Scale-12 (BSS-12), to assess 3 strengths: Temperance Strength, Intellectual Strength, and Interpersonal Strength. Two studies were conducted. Study 1 was conducted in Hong Kong. Service recipients (n = 149) from a psychiatric rehabilitation organization were recruited to establish the factor structure and construct validity of the BSS-12. In Study 2, 203 university undergraduates from mainland China were recruited to examine the factorial invariance of the BSS-12 in a different culture and population. Each factor demonstrated satisfactory internal consistency, content validity, and discriminant validity. The BSS-12 may be a useful tool for assessing strengths in clinical and nonclinical settings for service planning and the evaluation of intervention effectiveness.