As part of the State Targeted Response to the opioid epidemic, California has adopted the Hub and Spoke model to expand access to medications for opioid use disorder, particularly buprenorphine, throughout the state. By aligning opioid treatment programs as hubs with primary care, office-based practitioners, and other health care settings as spokes, a broader treatment model can reach more people with opioid use disorder, improve access to medications for opioid use disorders, and decrease overdose deaths. Expanding access requires expanding knowledge and intensive implementation support of new practices. This paper describes the rationale, specific activities and anticipated impact of the implementation plan in California's Hub and Spoke system. Training and technical assistance are designed to: increase the number and capacity of waivered prescribers; enhance skills of prescribers and multidisciplinary teams; and create systems change. Activities include buprenorphine waiver trainings and provider support, a practice facilitator program, Project ECHO sessions, webinars, clinical skills trainings, and regional learning collaboratives. This overview highlights the steps California is taking to build treatment capacity to address the opioid epidemic.