The purpose of this study was to investigate the impact of a professional development (PD) workshop on teachers' knowledge and use as related to the integration of online resources. In addition, this study attempted to examine whether teachers' aptitude was a moderating factor in the impact of the PD workshop. Moreover, it explored how teachers used online resources in their practice and how teachers' aptitude might affect their behavior. Based on problem-based learning, the PD workshop was designed to teach inservice teachers the use of a software tool, the Instructional Architect, and the integration of online resources into instructional activities intended for student use. This mixed-method study employed both quantitative and qualitative methods. A quantitative phase of research, a nonequivalent control group pretest-posttest design, as well as a qualitative phase of research, was employed. A repeated measures MANCOVA indicated that the PD workshop had a significant impact on improving teachers' knowledge and use. On the other hand, aptitude was not a moderating factor in the impact of the workshop. In addition, the qualitative phase suggested that while different aptitude teachers behaved similarly regarding how they used online resources, low aptitude teachers appeared to have the most positive attitudes toward the workshop. [For the complete volume, "Educational Media and Technology Yearbook, Volume 34," see ED602586.]