Degree: Master of Science Abstract: The present research examined social motivation in dementia within the theoretical framework of socioemotional selectivity theory (SST; Carstensen, 2006). SST is a lifespan theory of social motivation that argues goal selection and pursuit are inextricably related to perceived time remaining in life. When the future is perceived as expansive (as in youth), knowledge-related goals and novel social partners are prioritized. When constraints on time horizons are perceived (as in old age), emotion-regulation goals and familiar social partners are emphasized. Evidence reveals that social goals impact cognition. Termed the positivity effect, older adults, relative to younger adults, often demonstrate superior processing of positive stimuli and/or reduced processing of negative stimuli. Although it is widely understood that dementia is associated with disorientation to time (e.g., clock and calendar), little is known about whether persons with dementia are also disoriented to perceived time remaining in life. The objectives of the present research were to examine how moderate severity dementia affects (1) subjective time horizons, (2) the relative prioritization of knowledge- and emotion-related goals, (3) mental representations of social activities, (4) social partner preferences, and (5) the processing of emotional information in attention and memory. To make comparisons across the adult lifetime and as a comparison to aging in the presence of dementia, our sample included twenty-five young adults (M = 22.48 years), young-old adults (M = 67.56 years), old-old adults (80.24 years), and twenty-six participants with dementia (M = 85.38 years). Results indicated that those with dementia remained relatively oriented to lifetime in that, similar to young-old and old-old adults, they believed they had less time remaining in life than young adults. Participants with dementia reported goals centered on emotion-regulation to a greater extent than those related to knowledge-acquisition. Three-way multidimensional scaling revealed common dimensions along which groups considered social activities and indicated that the salience of these dimensions varied across groups. Dimensions related to affect were most important to older adults (i.e., young-old, old-old, participants with dementia) and least important to young adults. The prominence of information seeking in mental representations of social activities also varied across groups: this dimension was least important to older adults and most important to young adults. Group differences in preference for familiar over novel social partners were not observed. We did not find evidence of the positivity effect in attention, however an examination of memory performance did support the presence of a memory advantage for positive over negative information. Old-old adults and participants with dementia recalled and recognized a higher ratio of positive-to-negative images than did young adults. Young-old adults performed comparable to young adults on a recall task, but recognized a higher ratio of positive-to-negative images that did young adults. Theoretical and practical importance of these findings is discussed.