Religious affiliations of brides and bridegrooms and other information from Iowa marriage records from 1953 through 1957 were used to test hypotheses for the relations between religious endogamy norm saliency and possible reference group experience differences. Religious endogamy rates were used as direct measurements, and interreligious marriage rates were used as inverse measurements of religious endogamy norm saliency. The separate and joint ages of the brides and bridegrooms, their age differences, the status levels of the bridegrooms, the state of residence of the brides, and church or civil wedding ceremonies were used as measures of reference group experiences which might differentially affect religious endogamy norm saliency. Ten hypotheses were tested separately for the first-marriage and the remarried populations in Iowa for the period of observation. The analyses were restricted to religiously endogamous or interreligious marriages involving Catholics, church-affiliated Protestants, persons who identified themselves only as Protestants but who were not affiliated with any particular denomination and persons who indicated that they had no religious affiliation.

In the first-marriage populations, the ages of brides and bridegrooms were separately and jointly related to religious endogamy. Peak endogamy occurred during the twenties. Interreligious marriage rates were greatest at the extreme ends of the age distributions. Religious endogamy norm saliency was not related to bride and bridegroom age differences. There was a slight direct association between norm saliency and the occupational status levels of the bridegrooms. The ages of the spouses and the status levels of the bridegrooms interacted most frequently to produce the highest interreligious marriage rates among couples where the spouses were 18 or younger or 30 and older and where the bridegrooms had lower status occupations. The highest rates of religious endogamy occurred among spouses in their early or middle twenties where the bridegrooms had high-status occupations. Religious endogamy norm saliency was lower for brides who were not residents of Iowa and for those whose were married in civil ceremonies.