Coparenting is a complex construct that shares characteristics with other areas of the family system. In an effort to increase clarity surrounding conceptualizations of coparenting, definitions are proposed based on the external (the who, what, and where) and the internal (the what) structures that bound the coparenting construct. A framework of 4 coparenting dimensions that cross methodological boundaries is presented, and includes coparenting solidarity, coparenting support, undermining coparenting, and shared parenting. In analyses of data collected longitudinally from 62 couples when children were aged 6 months and 3 years, the coparenting dimensions were for the most part significantly associated between and within mothers and fathers. Notably, undermining coparenting was negatively related to coparenting support for fathers, but unrelated for mothers. Links between several distinct indicators within each coparenting dimension and marital outcomes were assessed to demonstrate the ramifications for choosing one measure of coparenting over another.