It is well known that older adults are living longer and longer. The United States Census Bureau (2000) projected that by 2030 at least 72 million individuals or 19.6% of the total population in the United States will be over the age of 65 years. Scientific evidence has shown the aging process often leads to declining body function, chronic illness, disability, isolation, cognitive impairments, and burdensome care to family members. These factors contribute to more than 600,000 older Americans living in assisted living facilities (ALFs). This number is expected to increase 15-20 percent each year. However, little is known about the salient factors that contribute to successful adaptation of older adults living in ALFs. This gap of knowledge, inclusive of lack of appropriate instruments to measure the process, prompted the researchers to develop an instrument to identify and measure the salient factors of adaptation. The Roy Adaptation Model and actual statements of residents of three ALFs were used to develop a 50-item questionnaire. Exploratory Factor Analysis tested and validated the instrument with 100 residents living in ALFs. Negative and positive salient factors were identified. This research will hopefully contribute to designing interventions to assist individuals to make a smooth transition from home to assisted living.