ABSTRACT BACKGROUND An early sign of cognitive decline in older adults is often a disruption in social function, but our understanding of this association is limited. OBJECTIVE We aimed to determine whether those screening positive for early stages of cognitive impairment have differences across multiple dimensions of social function and whether associations differ by gender. DESIGN United States nationally representative cohort (2010), the National Social life, Health, and Aging Project (NSHAP). PARTICIPANTS Community-dwelling adults aged 62–90 years ( N  = 3,310) with a response rate of 76.9 %. MAIN MEASURES Cognition was measured using a survey adaptation of the Montreal Cognitive Assessment categorized into three groups: normal, mild cognitive impairment (MCI), and dementia. We measured three domains of social relationships, each comprised of two scales: network structure (size and density), social resources (social support and social strain), and social engagement (community involvement and socializing). We used multiple linear regression to characterize the relationship of each social relationship measure to cognition. KEY RESULTS Individuals screened as at risk for MCI and early dementia had smaller network sizes by 0.3 and 0.6 individuals ( p  < 0.001), and a 10 % and 25 % increase in network density ( p  < 0.001), respectively. For social resources, individuals at risk for MCI and dementia had 4 % and 14 % less social strain ( p  = 0.01), but only women had 3 % and 6 % less perceived social support ( p  = 0.013), respectively. For social engagement, individuals screened positive for MCI and dementia had 8 % and 19 % less community involvement ( p  = 0.01), but only men had 8 % and 13 % increased social involvement with neighbors and family members ( p  < 0.001), respectively. CONCLUSION Changes in social functioning provide an early indication to screen for cognitive loss. Recognition that early cognitive loss is associated with differences in social function can guide counseling efforts and help identify social vulnerabilities to ease the transition to overt dementia for both patients and caregivers.