While discussion of the criteria needed to assess learning objects has been extensive, a formal, systematic model for evaluation has yet to be thoroughly tested. The purpose of the following study was to develop and assess a multi-component model for evaluating learning objects. The Learning Object Evaluation Metric (LOEM) was developed from a detailed list of criteria gathered from a comprehensive review of the literature. A sample of 1113 middle and secondary students, 33 teachers, and 44 learning objects was used to test this model. A principal components analysis revealed four distinct constructs: interactivity, design, engagement, and usability. These four constructs showed acceptable internal and inter-rater reliability. They also correlated significantly with student and teacher perceptions of learning, quality, and engagement. Finally, all four constructs were significantly and positively correlated with student learning performance. It is reasonable to conclude that the LOEM is reliable, valid, and effective approach to evaluating the effectiveness of learning objects in middle and secondary schools. (Contains 6 tables.)