Conceptualizing wellness requires a systematic assessment with reliable, valid and accurate measurements. The purpose of the study is to develop both a valid and reliable scale to evaluate the wellness of emerging adults. This research is composed of three separate studies. In the first study, item pool was generated and content validity was evaluated. In the second study (n = 343), factor structure with exploratory factor analysis (EFA), convergent validity and internal reliability of the Wellness Scale for Emerging Adults (WSEA) were investigated. In the third study (n = 357), the factor structure of WSEA was determined by EFA and it was tested by confirmatory factor analysis (CFA) in a different sample. EFA results showed that WSEA had a single-factor structure and CFA results indicated that single-factor structure model showed acceptable fit. In addition, the internal consistency reliability coefficient of WSEA was calculated in the third study. Cronbach's alpha was calculated as .81 and .82, respectively in the second and third studies. The findings demonstrate that WSEA is a reliable and valid instrument.