The incidence of interfaith marriages depends upon how religion is mea
sured. In this study, Catholic mixed-marriage rates are examined among
a sample of approximately 600 currently married men and women. It is
shown that the incidence of intermarriage is substantially lower if cu
rrent religion is used rather than religious upbringing. It is further
shown that the Catholic effect on the odds of intermarrying has decli
ned over time, particularly for men and women born during the 1950s. P
ROBIT is used to estimate the likelihood that Catholics intermarry.