Most sociological research assumes that social network composition shapes individual beliefs. Network theory and research has not adequately considered that internalized cultural worldviews might affect network composition. Drawing on a synthetic, dual-process theory of culture and two waves of nationally-representative panel data, this article shows that worldviews are strong predictors of changes in network composition among U.S. youth. These effects are robust to the influence of other structural factors, including prior network composition and behavioral homophily. By contrast, there is little evidence that networks play a strong proximate role in shaping worldviews. This suggests that internalized cultural dispositions play an important role in shaping the interpersonal environment and that the dynamic link between culture and social structure needs to be reconsidered. (Contains 2 tables, 1 figure and 8 notes.)