An estimated 9 percent of adults in New York City (NYC) had major depression in 2016, and about 20 percent are likely have a mental health challenge in any given year. Furthermore, more than 40 percent of adults with serious mental illness either experience delays accessing needed mental health treatment or never receive it at all. To address these documented unmet mental health needs, the Mayor’s Office of Community Mental Health (OCMH) brought together city agencies, nonprofits, and community-based organizations in 2015 to support the mental health of all New Yorkers through 54 priority initiatives. One of these initiatives involved the provision of in-person Mental Health First Aid (MHFA) trainings, first to staff at city agencies and community-based organizations and eventually to all New Yorkers citywide—free of charge.