State mental health agencies have potential to enhance implementation of the Mental Health Parity and Addiction Equity Act (MHPAEA), particularly through collaborations with state insurance agencies. Little research, however, has examined state agencies’ MHPAEA implementation strategies. The study purpose was to describe the trend in collaboration between state mental health agencies and other state agencies to assist with MHPAEA implementation between 2010–2015 and characterize implementation strategies used. A content analysis of information in the State Mental Health Profiling System was conducted. In 2010, 54.9% of state mental health agencies anticipated involvement with MHPAEA implementation through collaborations with other state agencies, but only 23.5% were involved in 2012 and 11.8% were in 2015. Ongoing consultation (58.5%) and local technical assistance (14.6%) were the implementation strategies most frequently used. State mental health agency involvement with MHPAEA implementation though inter-agency collaboration has been limited. Future research should examine factors that influence such collaborations.