Merrell’s Strong Kids

Complementary Program

Merrell’s Strong Kids is a skills promotion program for students in pre-school through twelfth grade. The elementary school edition uses free-standing lessons to promote social and emotional learning. The program applies a cohesive and developmentally focused approach, applying effective instructional design principles to primary prevention programming. The program emphasizes skills that can address internalizing problems such as anxiety and depression. Each level of the program and associated lessons are presented in grade bands. As the programs move from the lower to upper grades, the content and activities reflect student maturation over time. Material for preschool (Strong Start: Pre-K) and kindergarten through 2nd grade (Strong Start: K-2) includes ten lessons. Material for 3rd through 5th grade includes twelve lessons. All lessons are designed to last approximately 30-75 minutes, with suggestions to divide content as needed. Optional scripting can facilitate efficient implementation, along with suggestions for modifying content within a grade band. An implementation checklist and brief assessment measures are included. Lesson content focuses on skills such as recognizing and understanding emotions in oneself and others, behavioral activation, managing stress, anger, and conflict, perspective taking (e.g., empathy) and problem-solving, cognitive reframing, identifying personal assets, and setting goals. Each lesson includes an instructor reflection section, optional mindfulness-based focusing activity, suggested children’s literature to enhance the learning, and suggestions for embedding lesson content and skills practice throughout the day. Merrell’s Strong Kids also provides strategies for making cultural adaptations in order to support all learners. This program is designated as complementary because materials are presented in grade bands versus differentiated by grade. Merrell’s Strong Kids is also available in Korean.

Implementation Support

Specific training is not required to use the curriculum and can be implemented by general educators and interventionists. However, professional development is available through the authors and is considered to be a valued component of implementation preparation. Training emphasizes the theoretical bases of the program and tips for effective implementation such as coordinating the program with behavioral supports, assessment, and the program into large and small-scale SEL initiatives. All trainings are experiential with opportunities for participants to practice the strategies, to reflect upon how the content will be applied in context, and ways to anticipate and work with challenging situations.

Ongoing support for implementation is offered and can be tailored to meet each school’s needs. This support may include check-ins that occur in person or remotely via email or phone.

Evidence of Effectiveness

Results from two quasi-experimental evaluations published in 2010 and 2014 respectively supported the effectiveness of Merrell’s Strong Kids for elementary school students. In sum, these evaluations included students who were in 3rd and 4th grade (N=106; White=84%) and 1st-6th grade (N=614; Hispanic=57% and White=40%). One evaluation found that 3rd and 4th grade students who participated in the program rated themselves higher on perceived SEL skills and competencies compared to students in the control group at post-test (outcomes reported 12 weeks after baseline) and at a 2-month follow-up. The 2nd evaluation found 1st-6th grade students who participated in the program experienced a decrease in internalizing behavior scores, perceived by their teachers, compared to students in the comparison group (outcomes reported 17 weeks after baseline).

Results from a quasi-experimental evaluation (QE) published in 2012 supported the effectiveness of Merrell’s Strong Start Pre-K program for young elementary students. This evaluation included 84 students who were in pre-Kindergarten (White = 26%, Hispanic = 67%). This evaluation found that pre-Kindergarten students who participated in the program had significant decreases in teacher-reported internalizing problem behaviors compared to students in the control group (outcomes reported 8 weeks after baseline). Additionally, teachers implementing Merrell’s Strong Start Pre-K program showed improvement in their teaching practices. More specifically, treatment teachers demonstrated significantly greater declines in self-reported student-teacher dependency and conflict compared to teachers in the control group (outcomes reported 8 weeks after baseline). 


Harlacher, J. E., & Merrell, K. W. (2010). Social and emotional learning as a universal level of student support: Evaluating the follow-up effect of strong kids on social and emotional outcomes. Journal of Applied School Psychology, 26, 212-229.DOI: 10.1080/15377903.2010.495903

Gunter, L., Caldarella, P., Korth, B. B., & Young, K. R. (2012). Promoting social and emotional learning in preschool students: A study of Strong Start Pre-K. Early Childhood Education, 40, 151–159. 

Kramer, T. J., Calderella, P., Young, K. R., Fischer, L., & Warren, J.S. (2014). Implementing Strong Kids school-wide to reduce internalizing and increase prosocial behaviors. Education &Treatment of Children, 37, 659-880.

Additional References:

Caldarella, P., Christensen, L., Kramer, T.J., & Kronmiller, K. (2009). Promoting social and emotional learning in second grade students: A study of the Strong Start curriculum. Early Childhood Education Journal, 37, 51–56. doi:10.1007/s10643-009-0321-4