The effects of a school-based social-emotional and character development program, "Positive Action," on the developmental trajectory of character development was evaluated using data from three randomized trials. Results come from (1) 4-years of data from elementary children in 20 Hawai'i schools, (2) 3-years of data from elementary children in 14 schools in Chicago, and (3) 3-years of data from elementary children in 8 schools in a southeastern state. Random intercept, multilevel, growth curve analyses supported recent research on the trajectory of character development, in that students in both control and "Positive Action" schools reported a general decline in the number of behaviors associated with character they endorsed in all three trials. However, the "Positive Action" intervention significantly reduced the declines in all three trials. Taken together, the three analyses give insight into the normative trajectory of behaviors associated with character and evidence for the effectiveness of "Positive Action" in helping children maintain a relatively beneficial, though declining, developmental trajectory. A further more in-depth analysis was run in Chicago, looking for multiple trajectories of character development and links to a distal outcome, as well as, the evaluation of "Positive Action." The same scale of positive behaviors associated with character was used in connection to delinquent behavior to determine multiple trajectories of character development. These trajectories were also connected to delinquent behavior recorded at the end of the study. Results suggested that two distinct groups existed in the Chicago data, identified both by their intercept and slope on positive behavior, and also by their level of delinquent behavior at the end of the study. The effect of "Positive Action" was similar on both of these groups. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]