Recent theory suggests that developmental idealism (DI) is an important source of variation and change in family behavior, yet this suggestion is largely untested at the individual level. This study examines the influence of DI beliefs and values on individuals' entrance into marriage. We hypothesize that when individuals and their parents endorse DI, they enter into marriage later or more slowly. We also hypothesize that two pathways connecting DI to marriage are the instillation of older timing attitudes and expectations of marrying at older ages. We test these hypotheses using panel data collected in Nepal from 2008 to 2014. When young people and their parents endorsed DI, the young people valued older ages at marriage and expected to marry later. Young people's own DI endorsement also delayed their entrance into marriage, but parents' DI did not.