Patient-centered outcomes research helps youth and families using behavioral health services make informed decisions about treatments to help them achieve the outcomes most important to them. However, there are few efforts to identify the outcomes valued by youth and families systematically. This project aimed to support the development of behavioral health services that deliver outcomes valued by families by identifying the outcomes that youth and young adults with behavioral health needs and caregivers say matter most to them. We engaged 34 youth and young adults (YYA) with behavioral health needs, alongside 42 caregivers from six U.S. regions, in two rounds of one-hour virtual focus groups. The initial round involved participants identifying what they hoped to gain from using behavioral health services for personal, familial, and parental or child well-being and the attributes of positive service experiences. We coded responses using qualitative analytical software, culminating in synthesized reports. Subsequently, the second round entailed participants' review and refinement of initial findings. Across sessions, each group reported the top three outcomes deemed most important for children, YYA, parents, families, and their service experiences. YYA identified being understood by others, improving their interpersonal relationships, and feeling heard as the highest priority behavioral health service outcomes. Caregivers of children and youth with behavioral health needs identified having accessible services that meet their needs, having providers that collaborate effectively with parents and other service systems, and experiencing consistent and continuous behavioral health care for their child as the most important behavioral health service outcomes. Both YYA with behavioral health needs and caregivers of children and youth prioritized gaining the necessary knowledge, resources, and tools to support their or their child's behavioral health. Additionally, both participant groups emphasized the importance of effective communication with providers, within their families, and with peers. Minimizing judgment and stigma from society, providers, and other professionals also emerged as a critical outcome for these groups. It is essential for research and policy development to focus on and cater to the outcomes that are important and valued by YYA and their families to maximize family engagement in care.