It is estimated that approximately 8 to12% of all youth can be classified as severely emotionally disturbed (SED) (Costello, Egger, & Angold, 2005; Kessler et al., 2012). These youth exhibit a wide range of mental health disorders and symptoms (e.g., depression, anxiety, difficulty with emotion regulation or executive functioning) (Costello et al., 2005), and the extent to which to which their functioning is impaired by these symptoms and challenges varies widely (Williams, Scott, & Aarons, 2017). Only 25% of any of these children and adolescents ever access any outpatient mental health treatment (Costello et al., 2005; Costello, Messer, Bird, Cohen, & Reinherz, 1998) and even fewer obtain the intensive Home and Community-Based Services (HCBS) needed to keep youth with the most significant impairments safely in their home and communities (Owens et al., 2002; Spiker, 2017). Home and Community-Based Services (HCBS) often include in-home therapy, case management, or therapeutic behavioral support services (Kernan, Griswold, & Wagner, 2003; Marcenko, Keller, & Delaney, 2001). Without HCBS, youth with the most significant behavioral healthcare needs are at greater risk for chronic or long-term placement in a residential setting in either a psychiatric, correctional, or foster placement (Hansen, Litzelman, Marsh, & Milspaw, 2004; Knitzer & Olson, 1982; Narrow et al., 1998). Many families cite expense and lack of sufficient health coverage as barriers to service use (Owens et al., 2002; Spiker, 2017). The only type of health coverage that routinely covers HCBS is Medicaid (Howell, 2004), leaving these services mostly inaccessible to families whose incomes are above the Medicaid means-test limits. In order to access public health insurance to fund the intensive mental health care needed for their child, many parents relinquish custody to the state—either through the child welfare or juvenile justice system (U.S. Government Accountability Office, 2003). States use a variety of policy interventions to reduce income barriers to HCBS for these youth, including Medicaid waivers, the TEFRA provision, and State Plan Amendments (Friesen, Giliberti, Katz-Leavy, Osher, & Pullmann, 2003; Ireys, Pires, & Lee, 2006). However, little is known about these strategies or state motivations for choosing one policy over another. Limited evaluation also exists regarding their relative effectiveness at meeting the needs of these youth and their families. Having knowledge of the variety of policy tools available to states and how states utilize these tools, as well as the factors that increase the likelihood that a state will opt to use a particular tool, will allow future research to control for such variables, and better discern the effects of the policy on state level mental health system outcomes. This two-part mixed methods study aims to discern state policies that are more and less effective at reducing access barriers to home and community-based mental health care for non-Medicaid eligible youth with SED. The first, qualitative portion of the study aims to 1) identify policy mechanisms utilized by states to deliver HCBS to youth with SED and their families, particularly for youth whose family income disqualifies them for Medicaid and 2) understand what motivates State Mental Health Authorities and Medicaid Agencies to utilize current policy tools and structures for HCBS delivery for both Medicaid and non-Medicaid eligible youth with SED. The second, quantitative analysis seeks to 1) assess the relationship between a state’s use of a Medicaid waiver and the odds that a youth with SED will have public health coverage, 2) assess the relationship between public health coverage and unmet mental health care needs and cost barriers to care for youth with SED, and 3) assess the direct relationship between a youth’s residence in a state with a Medicaid waiver, and the odds that the youth will have unmet mental health care needs and cost barriers to care. Part I of this study gathered qualitative data through semi-structured interviews with officials from 32 state mental health systems about policy tactics for funding and delivering HCBS to Medicaid and non-Medicaid eligible youth with SED in their state. Interviews also gathered information about each state administration’s motivation and history that shaped the use of current HCBS policies for this population. Part II of the study utilized data created from information and observations in Part I in conjunction with data from the National Survey for Children with Special Health Care Needs from 2009/2010. Multi-level, random-intercept logistic regression models assessed the relationship between Medicaid waivers and unmet mental health care needs and cost barriers to treatment for youth with SED. Results indicate that states use many strategies for funding and organizing care for the non-Medicaid eligible population of youth with SED, but that strategies generally involve the allocation of state general revenue funds or the use of a policy that expands the financial eligibility limits of Medicaid for children. Reasons for the use of each approach are most related to the size and flexibility of Medicaid budgets, political prioritization of children and families, and political ideology related to the role of the state in providing for the welfare of children and families. The quantitative analysis found that policies expanding financial eligibility for Medicaid were related to reductions in cost-related barriers to treatment, even controlling for the mediating effect of these policies in changing the insurance status of children. However, the use of these policies and a child's coverage under public health insurance was not significantly predictive of reduced odds of having unmet mental health care needs. By controlling for the severity of a child's mental health care needs, and the interaction between their level of need and type of health insurance coverage, this analysis also highlighted the role of clinical severity in unmet treatment needs and barriers to care and the ways in which public insurance moderated this relationship. This study concludes that, though states have many means of funding care for non-Medicaid eligible youth with complex behavioral healthcare needs and have various reasons specific to state environments for choosing a particular approach, states with policies that allow children to more easily access Medicaid appear to have fewer families experiencing cost barriers to mental health services. However, these state policies do not address other, unknown barriers to obtaining mental health services for families in their states. Expansion of Medicaid eligibility for children can help to reduce unmet need due to financial obstacles but does not solve all problems related to service accessibility. Additional barriers to treatment access must be identified at the individual, organizational and policy levels for children with all levels of clinical need. Policies and practices aimed at reducing these must be identified and implemented in the manner most suitable and applicable to the unique political, fiscal, and structural concerns of each state and community. Then, these practices and policies must be rigorously evaluated for effectiveness in achieving equitable access to high quality and effective mental health treatment for all children with behavioral health concerns.