Throughout the 1990s, assisted living was the most rapidly growing form of senior housing. The purpose of this paper is to describe the existing supply of assisted living facilities (ALFs) and examine the extent to which they matched the philosophy of assisted living. The study involved a multistage sample design to produce nationally representative estimates for the ALF industry. Administrators of nearly 1,500 eligible ALFs were interviewed by telephone. As of 1998, there were an estimated 11,459 ALFs nationwide, with 611,300 beds and 521,500 residents. Nearly 60% offered a combination of low services and low or minimal privacy, whereas only 11% offered relatively high services and high privacy. Seventy-three percent of the resident rooms or apartments were private. Aging-in-place was limited by discharge policies in most ALFs for residents who needed help with transfers, had moderate to severe cognitive impairment, had any behavioral symptoms, or needed nursing care. The industry is largely private pay and unaffordable for low- or moderate-income persons aged >/=75 unless they use assets as well as income to pay. ALFs differed widely in ownership, size, policies, and the degree to which they manifested the philosophy of assisted living. This diversity represents a challenge for consumers in terms of selecting an appropriate facility and for policy makers in terms of deciding what role they want assisted living to play in long-term care.