Due to the growing interest in holistic health and well-being, the Mental, Physical, and Spiritual Well-being Scale was developed. This well-being scale has 30 items and incorporates mental, physical, and spiritual subscales. An initial set of items was developed and 186 university students responded to these. An exploratory factor analysis was conducted using principal components analysis with varimax rotation (N=100) to reduce the number of items in the scale. Three factors were extracted based on the eigenvalues, loading coefficients exceeding 0.3, and the scree test. Ten items from each of the three factors were selected, reducing the number of items from 66 to 30. Another factor analysis, performed on 129 employees of the Commonwealth Scientific and Industrial Research Organisation and 229 students from Monash University, indicated three factors were representative of the mental, physical, and spiritual subscales. Test-retest reliabilities over 1 mo. ranged from 0.87 to 0.97 for the three subscales whilst internal consistency ranged from 0.75 to 0.85. Concurrent validity was examined using the General Health Questionnaire and the Spiritual Well-being Scale. The discriminant validity of the MPS was also explored using three activity groups nominated as highly physical (weight training) or highly mental (chess) or highly spiritual (prayer). Our of a total of 88 cases, 77.3% of these were correctly classified into their actual activity group based on their scores. Sample sizes were moderate and testing was of limited samples. More psychometric work is needed but preliminary findings indicate an accurate and reliable test.