As a head nurse in pediatrics and staff nurse in intrapartum, postpartum, and newborn nursery units, Ramona Mercer had a great deal of experience in nursing care for mothers and infants. This gave her a strong foundation for creating her Maternal Role Attainment Theory for nursing.

The Maternal Role Attainment Theory was developed to serve as a framework for nurses to provide appropriate health care interventions for nontraditional mothers in order for them to develop a strong maternal identity. This mid-range theory can be used throughout pregnancy and postnatal care, but is also beneficial for adoptive or foster mothers, or others who find themselves in the maternal role unexpectedly. The process used in this nursing model helps the mother develop an attachment to the infant, which in turn helps the infant form a bond with the mother. This helps develop the mother-child relationship as the infant grows.

The primary concept of this theory is the developmental and interactional process, which occurs over a period of time. In the process, the mother bonds with the infant, acquires competence in general caretaking tasks, and then comes to express joy and pleasure in her role as a mother.

The nursing process in the Maternal Role Attainment Theory follows four stages of acquisition. They are: anticipatory, formal, informal, and personal. The anticipatory stage is the social and psychological adaptation to the maternal role. This includes learning expectations and can involve fantasizing about the role. The formal stage is the assumption of the maternal role at birth. In this stage, behaviors are guided by others in the mother's social system or network, and relying on the advice of others in making decisions. The informal stage is when the mother develops her own methods of mothering which are not conveyed by a social system. She finds what works for her and the child. The personal stage is the joy of motherhood. In this stage, the mother finds harmony, confidence, and competence in the maternal role. In some cases, she may find herself ready for or looking forward to another child.