While human service clients often interface with numerous systems, the administrative data depicting their system interactions are often held in institutional silos, thus limiting the ability of analyses to generate nuanced insights about the whole person. However, when shared and integrated across agencies, administrative data can be used to address complex social policy issues and ultimately improve lives. This three-paper dissertation illuminates the underlying theories and methods for building integrated data capacity in human service agencies while also demonstrating the value of bringing together cross-agency administrative data for a particular social policy issue—youth mental health service quality. The first paper examines current theories around administrative data integration. Then, theory synthesis methods are used to apply critical theory and social constructionism and build an updated theoretical framework for the field. The second paper draws on these theoretical tenets while using integrated datasets from the State of Rhode Island to analyze factors associated with quality mental health service receipt for children and youth. Logistic regression results show that transition age youth and youth who recently experienced a pregnancy, juvenile justice involvement, parental substance use, or job loss in the household may be less likely to receive minimally adequate follow-up care after a mental illness hospitalization. Youth who may be more likely to receive follow-up care include those with longer hospital stays; parents with prior mental health claims; or primary diagnoses of depression, bipolar, or other mood disorder; anxiety, OCD, or fear disorder; or a schizophrenia or psychotic disorder. In addition, the second paper quantitatively analyzes the value of integrating data and shows that the model containing variables from four source systems may be most beneficial to analyzing receipt of quality care. While these quantitative analyses were conducted, observational fieldnotes were also collected to illuminate the process and lessons learned from engaging with partners in Rhode Island. These data were analyzed and reported on through a qualitative case study in the third paper, ultimately showing a realistic timeline and process for aligning research, policy, and practice partners around the use of integrated data as well as five key lessons learned for partnership-engaged research.