The benefits of peer evaluation of teaching effectiveness and quality in higher education are well documented. While instruments exist for the review and evaluation of entire online courses, there is no standardized single-lesson, peer evaluation instrument available for online instruction. This pilot study focused on the validation of a peer observation and evaluation tool for use with single lessons in both synchronous and asynchronous online courses in an inter-professional school of health professions. The researchers modified a psychometrically validated instrument developed for in-person peer observation by adding items from a renowned online course rubric to create a peer observation tool, entitled the Peer Observation and Evaluation Tool-Online (POET-O). The resulting instrument demonstrated adequate construct validity and reliability by using the many-facet Rasch measurement (MFRM) technique. MFRM results also indicated potential places to revise and improve the instrument. Recommendations for implementing the peer evaluation process of teaching are provided.