This dissertation uses two nationally representative surveys which span from young
adulthood to late life to examine social isolation across the adult life course in the United States.
In the first chapter of this dissertation, I examine patterns and trends of social isolation by age,
period, cohort, and gender by conducting descriptive analyses using the National Survey of
Midlife Development in the United States (MIDUS) and the Health and Retirement Study
(HRS). I find that about 14 percent of U.S. adults aged 25 and older are socially isolated with
this percentage growing with advancing age as well as across period-based time. Additionally,
there are gender differences in social isolation which vary based on whether relationship status is
included or excluded from the measure of social isolation.
In the second chapter, I investigate the trajectory of social isolation across the adult life
course and examine how social isolation varies by cohort and gender. This is done by testing five
longitudinal models of social isolation: enduring, spontaneous, lagged effects, life course, and
hybrid, using both MIDUS and HRS. This chapter shows that social isolation is relatively stable
within people as they age through adulthood, which is due to both time-invariant factors and
recent history. More recent birth cohorts have higher levels of social isolation. Additionally,
while men are more isolated than women earlier in adulthood, these disparities converge before
reversing at later ages.
My third chapter examines the relationship between social isolation and self-rated health
across adulthood and how this relationship differs by gender, again using MIDUS and HRS. This
chapter demonstrates that social isolation and self-rated health influence each other in older
adulthood, but not in early adulthood or midlife. There are few gender differences in the
relationship between social isolation and self-rated health across adulthood, except that women
in older adulthood may experience greater health risks to being socially isolated than men.
In sum, this dissertation advances understanding of social isolation across the adult life
course in the United States by evaluating trends within and between-individuals across time,
examining connections between social isolation and health, and assessing gender differences.