Along with socio-economic changes in Iran, the family formation (marriage) has also changed and departed from its earliness and generality nature. The age at marriage has increased and the increase was sharper for highly educated people. Two questions can be raised: are these changes a result of adaptation to new conditions provided by the modernization process? Or are they a result of temporary crises caused by social and economic problems? This paper aims to answer the questions using data from a survey on the ideal age of marriage among postgraduate students at the University of Tehran in 2012. Independent variables include meta-materialism, opportunity costs, loss of family-centered values, person-centered values, attitudes towards male and female friendship before marriage (as indicators of adaptation), economic problems, and social problems (as indicators of the crises). The results show that opportunity costs positively and family-centered values negatively affect male students' ideal age of marriage. Meta-materialism, opportunity costs and positive attitudes related to male and female friendship have positive effects on female students' ideal age of marriage.