OBJECTIVE. We describe the development of a questionnaire, Participation in Activities and Places Outside Home (ACT-OUT), for older adults with cognitive impairment and align it to people with mild-to moderate-stage dementia. METHOD. ACT-OUT was developed in a cross-cultural collaboration in combination with three rounds of cognitive interviews in Switzerland with 26 older adults without cognitive impairment and five older adults with dementia. Qualitative data from the interviews were analyzed using a constant comparison approach. RESULTS. The final ACT-OUT Version 1.0 consists of three parts: (1) questions targeting places older adults visit; (2) questions on aspects influencing participation, such as transportation, familiarity, and risk perception; and (3) questions on perception of self. CONCLUSION. The development of an instrument such as ACT-OUT is more a cyclical than a linear process. This study is a first step toward a more systematic evaluation of out-of-home participation among older adults with and without dementia. O lder adults with dementia and their significant others value participation in activities outside the home, such as grocery shopping, pharmacy visits, and dog walking (Egan et al., 2006; Teitelman et al., 2010). Participation in outside activities offers numerous benefits, including maintaining cognitive functioning and autonomy, keeping in touch with others, and exercising in nature (Rao et al., 2014; Sugiyama & Ward Thompson, 2007; Winchester et al., 2013). It also involves an endless variety of places in combination with activities in which older adults want and need to engage. Being immersed in activity in places-being in place-is an ongoing life process that generates important meaning (Rowles, 2008). It is closely related to the process of place integration-the continual adjustment of person-place relationships to enhance well-being (Cutchin, 2004)-and is consistent with the transactional perspective on occupation: Participation in occupation is seen as fundamental to the functional coordination of person and place in response to problematic situations (Cutchin & Dickie, 2013; Dickie et al., 2006). Person-place relationships may change in relation to the development of dementia as the relationships that were once central to one's life are disrupted by loss of familiarity, loss of ability to navigate and access places, or fear of embarrassment. These changes can have a cascading effect on participation and amplify risk of further disengagement. Thus, having regular access to outside places and activities is critical for maintaining familiarity for people with dementia (Brorsson et al., 2011). The interdependency of places and activities can facilitate or hinder participation, for example, through distances and layout of the physical environment, availability of transportation and support, meaning of activities, risk perception, and familiarity. Maintaining a level of out-of-home participation can be a complex endeavor for people with dementia, who face challenges such as getting los...