The Survey of Income and Program Participation (SIPP) is the first nationally representative survey to ask a direct question on multiple partner fertility (MPF) to men and women. Much of the current research on MPF has looked at its prevalence among contemporary families. Using the unique fertility history questions in the SIPP, this research takes an historical perspective to analyze the prevalence of MPF across birth cohorts and within specific parities. We also present estimates by birth cohorts within race and Hispanic origin groups. These findings will provide new insight into the childrearing experiences of older generations, which can be masked when only looking at total number of children ever born.