This study examined the action research reports written by teachers in one Florida school district after they had received professional development on differentiated instruction and the action research process in the 2009-2010 school year. The 69 reports that were completed by the teachers were assessed using the Action Research Rubric that was developed for this study. This rubric evaluated whether the reports contained the elements of action research along with the characteristics that the district emphasized as part of the professional development such as differentiation, student subgroups, and collaboration. The Action Research Rubric contained seven subscales: Purpose of the Study, Plan, Professional Collaboration and Resources, Data and Evidence, Results, Instructional Decisions and Professional Reflection, and Sharing Results. Descriptive statistics were found for the aggregate group of reports as well as subgroups depending upon the school level (elementary, middle, or high school), the types of teachers within the elementary category, or the FCAT subject area of focus for the report. Overall, the action research reports met the district‟s standard as measured by the Action Research Rubric. As an aggregate group, the reports also met the standard on the Purpose of the Study, Professional Collaboration and Resource, and Data and Evidence Subscales. They did not perform as well on the Plan and Sharing Results Subscales.