The purpose of this study is to confirm the working hypothesis on two major models of functioning decline and two corresponding models of rehabilitation program in an older population through detailed interviews with the persons who have functioning declines and on-the-spot observations of key activities on home visits. A total of 542 community-dwelling older persons (65 years and older) in a suburban city, who were qualified for the services of the Insurance for Long-term Care were visited at their home and they gave two types of interviews: a preliminary semistructured one using an International Classification of Functioning, Disability and Health-based questionnaire and the main detailed one combined with observation of performance of key activities both within and around the home. The results confirmed the two major models of functioning decline and corresponding rehabilitation program: "stroke model" (acute onset type) was observed in 271 (50.0%) persons and "disuse syndrome model" (chronic progression type) was observed in 226 (41.4%) persons, along with an additional other model (on account of cognitive problems) in 45 (8.3%) persons. This result confirms that disuse syndrome (deconditioning) should be recognized as an important cause of functioning decline in the older population and a corresponding model of the rehabilitation program should be consciously pursued. This recognition of the importance of disuse syndrome will have a strong impact on clinical thinking about the rehabilitation of the older population.