© Cambridge University Press 2010. Abstract The purpose of this chapter is to provide a conceptual basis for using life-space to assess mobility resilience and maintenance of social participation among community dwelling older adults. The Life-Space Assessment (LSA) measures mobility and the geographic scope of participation in society over one month. It reflects distance, frequency, and use of equipment or personal help while ambulating through the environment. An LSA score of 60 or higher defines an unrestricted life-space – a level of mobility and participation that operationalizes resilience among older adults. After reporting results of a qualitative study examining attitudes toward life-space mobility, we report cross-sectional and prospective data from an observational cohort study of community-dwelling older adults. Significant associations between life-space mobility with social participation, as well as specific correlates and predictors of life-space mobility resilience, are defined. The importance of life-space resilience as a reflection of mobility and social participation among community-dwelling older adults An important aspect of resilience is the ability to maintain function in the context of chronic disease and age-associated physiological changes. Available data suggest that 80 percent of persons over the age of 65 years have at least one chronic condition and 20 percent have four or more such conditions (Chodosh et al., 2005). Age-associated physiological changes have been well documented in all organ systems (Hazzard et al., 2003).