Adolescents in the United States are in a mental health crisis. It is estimated that more than 20% of children ages nine to 17 struggle with behavioral, emotional, and social problems and mental health disorders such as anxiety, depression, or post-traumatic stress disorder (PTSD) (U.S. Department of Health and Human Services, 1999). Mental health and social emotional wellness have become a significant area of concern for elementary, middle, and high school students and have been exacerbated by school violence, bullying, academic stressors, and personal challenges. In a publication by the Mental Health Association in New York State, Inc., Richter (2017) indicated that half of all chronic mental health conditions "begin by age 14, half of all lifetime cases of anxiety disorders begin as early as age eight and some 22% of youth aged 13-18 experience serious mental disorders in a given year" (p. 7). This study focused on how to integrate mental health and social-emotional wellness effectively and efficiently into the Multi-Tiered Systems of Support (MTSS) and Interconnected Systems Framework (ISF) to provide tiered levels of intervention which includes proactively identifying the mental health and social-emotional needs of students and then systematically providing them supports and interventions to meet those needs to improve academic outcomes. Specifically, the purpose of this quantitative correlational study was to explore the relationship between the beliefs and actions of secondary school principals, in schools including grades 9-12 or grades 9-12 and any combination of 6-8 in one building, and the implementation of mental health and social-emotional interventions and supports as components of existing Multi-Tiered Systems of Support (MTSS). The Multi-Tiered Systems of Support (MTSS) framework and Interconnected Systems Framework (ISF) were used as structures for providing secondary school students with mental health and social-emotional interventions and supports. Effective implementation of these frameworks was examined through Fixsen et al.'s (2005) core components of implementation science, and the role of the secondary school principal through the lens of Heifitz et al.'s (2009) adaptive leadership model. A researcher developed survey, created in SurveyMonkey®, was emailed to 586 secondary school principals. Anonymous survey results from 56 respondents (9.6% response rate) were analyzed to develop findings, conclusions, and recommendations. The primary conclusion from the research indicates that while secondary school principals believe that the mental health and social-emotional wellness of students is a concern, there is a need for effective systems and structures to be put into place to ensure responses to student needs are more proactive than reactive. [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.]