The purpose of this study was to develop a reliable and valid instrument to measure self-directedness in learning among college students based on an operationalization of the personal responsibility orientation (PRO) model of self-direction in learning. The resultant 25-item Personal Responsibility Orientation to Self-Direction in Learning Scale (PRO-SDLS) was found to be a highly reliable instrument in the selected sample of graduate and undergraduate education students. Confirmatory factor analysis established that a four latent variable model fit the data. Scores from the PRO-SDLS were significantly related to criterion variables thought to demonstrate self-direction and to a known instrument of self-direction while accounting for additional variance. Recommendations for further research in the ongoing process of scale validation and implications for practice are provided. (Contains 5 tables and 2 figures.)