Unstable couple relationships and high rates of repartnering have increased the share of U.S. families with stepkin. Yet data on stepfamily structure are from earlier periods, include only coresident stepkin, or cover only older adults. In this study, we use new data on family structure and transfers in the Panel Study of Income Dynamics (PSID) to describe the prevalence and numbers of stepparents and stepchildren for adults of all ages and to characterize the relationship between having stepkin and transfers of time and money between generations, regardless of whether the kin live together. We find that having stepparents and stepchildren is very common among U.S. households, especially younger households. Furthermore, stepkin substantially increase the typical household’s family size; stepparents and stepchildren increase a household’s number of parents and adult children by nearly 40 % for married/cohabiting couples with living parents and children. However, having stepkin is associated with fewer transfers, particularly time transfers between married women and their stepparents and stepchildren. The increase in the number of family members due to stepkin is insufficient to compensate for the lower likelihood of transfers in stepfamilies. Our findings suggest that recent cohorts with more stepkin may give less time assistance to adult children and receive less time assistance from children in old age than prior generations.