The purpose of this study was to assess differences in trends between 13 special education diagnostic eligibility categories over time in California. A secondary purpose was to determine whether differences occur among county types (rural, urban, or other) or between regions (Northern or Southern California). Analysis of descriptive statistics revealed that changes have occurred over time within the 13 eligibility categories between the years 2002, 2004, 2006, 2008, and 2010. Thirteen repeated measure ANOVAs were performed, one for each eligibility category, with the dependent variable being percentage and the independent variable year. Results indicated that the SLD category demonstrated a significant decrease between 2002 and 2010. Categories with significant increases between 2002 and 2010 included OHI, AUT, ED, HOH and DB. Categories which did not demonstrate significant changes included SLI, ID, DEAF, VI, OI, MD and TBI. To determine whether significant changes occurred between Northern and Southern California regions, 5 Profile Analyses were performed, 1 for each year studied. The results indicated no significant differences between Northern and Southern California. A second set of profile analyses were run, 1 for each year, to determine whether there were significant differences between rural, urban, and other county types. The results indicated that for each year, there were significant differences between county types, with lowest percentages of SLD occurring in urban counties. SLI and OHI were highest in urban counties. The category of AUT was highest in rural county types. Practical and scientific significance of these eligibility changes was discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]