Methods: The proposed study is a, parallel design, intention to treat, randomized clinical trial comparing the AHCM intervention to a time and attention control (weekly housing group) among homeless Veterans (N=400) newly entering addiction treatment. Following baseline assessment, Veterans will be randomly assigned, stratified by gender and primary substance problem, to one of the two treatment conditions and followed for 12 months. All Veterans will receive addiction treatment as usual. Veterans assigned to the AHCM condition will have a case manager who is integrated with the interdisciplinary treatment team. The AHCM will meet with the Veteran weekly, assist the Veteran with potential housing options, support the Veteran in continuing addiction treatment and psychiatric care, visit the Veteran in the community when appropriate, and obtain point of care urine toxicology testing to assess abstinence with the goal of addressing substance use issues proactively. The AHCM will educate the Veteran on needed basic life skills using existing manuals. Veterans assigned to the control condition will attend a weekly housing group where housing options are discussed. Participants will complete research assessments every 3 months through one year and then every 6 months for up to 2 years post-randomization to assess housing status and other outcomes. The Northwest Regional Data Warehouse and Decision Support System data sources will be used to determine outpatient and inpatient VA health care services and costs for the 1 year before and 2 years after study enrollment.