Several social-emotional learning (SEL) or social-emotional and character development (SECD) programs have been shown to be effective at improving SEL/SECD skills, and some have also provided evidence of effectiveness in improving student behavior and academic achievement (Durlak, Weissberg, Dymnicki, Taylor, & Schellinger, 2011). Very few SEL or SECD programs have replicated effects for all three of these domains of outcomes with students of different cultural/ethnic backgrounds in schools of different socioeconomic status and urbinicity. In education research, replication with different populations in different settings is important for understanding the generalizability of findings. In this paper, the author reports results from two cluster-randomized trials of the SEL/SECD program, "Positive Action" ("PA") across two very different groups of students and contexts: (1) 20 suburban and rural elementary schools (specifically grades 2/3 to grades 5/6) on three Hawai'i islands in 2002-2006; and (2) 14 high-poverty, inner-city Chicago elementary schools (specifically grade 3 to grade 8) in 2004-2010. One table is appended. [The initial phase of the Chicago trial (R305L030072), a component of the Social and Character Development (SACD) Research Consortium, was a collaboration among Institute of Education Sciences (IES), the Centers for Disease Control and Prevention's (CDC) Division of Violence Prevention, Mathematica Policy Research Inc. (MPR), and awardees of SACD cooperative agreements (Children's Institute, New York University, Oregon State University, University at Buffalo-SUNY, University of Maryland, University of North Carolina-Chapel Hill, and Vanderbilt University).]