CASES will improve and advance the Nathaniel CCBHC (NCCBHC), located on the 125th Street corridor in Central Harlem. The NCCBHC will provide rapid access, high-fidelity integrated care for Central Harlem residents, who experience some of NYC's highest rates of psychiatric and substance use-related hospitalization, and people involved in NYC's criminal justice (CJ) system who are in the community under Court supervision and experience high rates of SMI, SED, SUD, and homelessness. The NCCBHC will provide services to people not connected to care, including 1) residents of Central Harlem--a majority Black (55%) and Latino (22%) community in which 25% live below the poverty line--who in addition to some of NYC's highest rates of psychiatric and substance use-related hospitalization experience the highest citywide rate of resident incarceration, and 2) people involved in NYC's CJ system, including who are recruited and connected to NCCBHC from CASES' co-located Pretrial and Alternative-to-Incarceration (ATI) Programs. These Pretrial and ATI Programs annually divert more than 6,000 youth and adults from New York County (Manhattan) Family, Criminal, and Supreme Courts, among whom the highest concentration citywide reside in Harlem. Consistent with the intersection of racial, ethnic, socioeconomic, and health disparities with involvement in the CJ system, the people served by NCCBHC are predominantly Black (68%), Latino (36%), male (62%), and young (48% ages 18-34), with 38% female, 10% LGBTQI+, 4% ages 13-17 (33% with SED) 20% ages 35-44, and 26% ages 45+. More than one in three (35%) are Harlem residents, 68% have CJ involvement, 69% have SMI, 25% have SUD, and 18% are homeless. Nearly one in three (31%) are CJ-involved Black men. With a CCBHC-IA grant, NCCBHC will strengthen model implementation by expanding peer support, targeted case management, and SU services including to support three core improvements: 1) achieving same-day access for initial evaluation for all people new to the clinic seeking walk-in services regardless of level of need; 2) decreasing wait times for initial evaluation for people seeking non-crisis services; and 3) increasing treatment utilization among the focus population of CJ-involved New Yorkers including CJ-involved Black men. These improvements will promote recovery for 1,400 people engaged in NCCBHC over the four-year grant (300 in Year 1, 360 in Year 2, 360 in Year 3, and 380 in Year 4). The targeted enhancements related to increased access and engagement--and improved health--correlate with successful completion of Court supervision requirements for CJ-involved people with SMI and/or SUD in the community with open cases. While 50% of participants with SMI and/or SUD successfully complete CASES Pretrial Services--thereby completing Court supervision-90% of Pretrial participants with SMI and/or SUD co-enrolled in NCCBHC treatment services successfully complete Court supervision and thus avoid jail detention.