In this article we present the development and validation of two new measures of psychological well-being: the Comprehensive Inventory of Thriving (CIT) and the Brief Inventory of Thriving (BIT). These measures were developed with two specific goals in mind: (1) to measure a broad range of psychological well-being constructs and represent a holistic view of positive functioning; and (2) to predict important health outcomes that are useful for researchers and health practitioners. The CIT includes 18 subscales with 54 items in total, covering a broad range of well-being components. The BIT has 10 items in total and can serve as an indicator of psychological well-being and a brief screening tool of mental health. The new measures were evaluated in five samples of a total of 3,191 US participants with diverse demographics. The CIT and BIT had excellent psychometric properties and exhibited convergent validity with existing measures of psychological well-being and discriminant validity with measures of ill-being. Both measures contributed over and above existing measures of psychology well-being in predicting a variety of health outcomes, including self-reported and objective health status, physical functioning, and health behaviors. In addition, we showed the relative importance of thriving compared to ill-being for health outcomes and the benefits of assessing individuals' positive functioning beyond ill-being. Potential uses of the new measures are discussed.