Using data from the Fragile Families and Child Wellbeing Study (N = 3,003), we examine the role of parental relationship status at birth on maternal adherence to current recommendations regarding breastfeeding, corporal punishment, and well-child visits. At the bivariate level, parents' union status is almost linearly related to adherence to recommendations. Multivariate models, however, reveal that much of the association stems from the selection of more advantaged individuals into more serious relationships. The results suggest that, although relationship status may be an accurate indicator of parents who are at risk of not adhering to recommended parenting behaviors, the underlying causes of nonadherence are more complex.