Homeless Services United (formerly the Council on Homeless Policies and Services) was formed in July 2003 following the merger of two membership organizations, each representing a distinct sector of nonprofit homeless services providers in New York City: the Tier II Coalition consisted of agencies serving homeless families and the Association of Service Providers to Homeless Adults (ASPHA) consisted of agencies serving homeless, single adults.

In 1992, Tier II shelter directors met to coordinate advocacy efforts during the Giuliani administration. The group quickly realized that strong, effective advocacy required city-wide collaboration and a more formalized organizational structure. As a result, they incorporated to form the Tier II Coalition.

The Association of Service Providers to Homeless Adults (ASPHA) was formed in 1998 when a group of homeless services agency executives decided that a provider coalition would be a valuable means to maximize information sharing among various agencies serving single adults and would strengthen service providers' ability to shape public policy.

Soon, it became clear that there was significant overlap in the coalitions' memberships, as well as their advocacy agendas, and the Tier II Coalition and ASPHA began pooling resources and working together on joint advocacy initiatives. In 1999, the two organizations hired a joint Executive Director. In July 2003, they merged to form the Council on Homeless Policies and Services, today known as Homeless Services United (HSU).