How do personal networks evolve as individuals age? To what degree do social disadvantage and contextual factors matter for network dynamics in later life? This paper answers these two questions based on egocentric network data of older adults over a ten-year period. Specifically, I use longitudinal and nationally representative data on 1,168 older adults from the National Social Life, Health, and Aging Project. I use between-within models to separate the within- and between-individual effects of sociodemographic characteristics and contextual factors on three aspects of social connectedness in later life: network size, frequency of contact, and proportion of kin. Patterns of network change vary among people of different races and ethnicities as well as educational levels. Black and Hispanic respondents have a significantly smaller network size and a higher average frequency of contact with confidants. Moreover, Hispanic respondents have a higher proportion of kin in the network, compared to White respondents. Similarly, older adults with less education have a smaller network size, higher frequency of contact and higher proportion of kin in their confidant networks compared to those who attended college. Older adults who have better mental health are more likely to have a higher frequency of contact and higher proportion of kin. When an older adult starts to work for pay, their frequency of contact with confidants tends to increase. Older adults living in neighborhoods with stronger social ties are more likely to have a larger network size, higher frequency of contact, and lower proportion of kin in their confidant network. The above results show that disadvantaged backgrounds and contextual factors are associated with certain less favorable network characteristics, which helps to explain the concentration of social disadvantage on certain populations.