Online learning is variously employed in K-12 education, including for teacher professional development. However, the use of computer-based technologies for learning purposes assumes learner computer proficiency, making this construct an important domain of procedural knowledge in formal and informal online learning contexts. Addressing this concern, this study examined the score properties and invariance (N = 11,709) of an eight-item self-report measure of computer proficiency for online learning, the CPOL. Results from a confirmatory factor analysis suggest that the hypothesized unidimensional structure undergirded the instrument's scores, and invariance analyses suggested that the instrument functions similarly across teacher populations defined by gender, grade level taught, and age, and over time. Specifically, the results showed "strict" score invariance for all teacher groupings except for age. Discussed are potential proximal and distal applications of, and directions for future research concerning the CPOL.