Date of Award

Summer 2012

Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Diana Robins, Ph.D.

Second Advisor

Frank Floyd, Ph.D.

Third Advisor

Lisa Armistead, Ph.D.

Fourth Advisor

Lindsey Cohen, Ph.D.

Fifth Advisor

Chris Henrich, Ph.D.


This study assessed marital quality, coparenting, and parenting stress over time for parents of children with intellectual disability by creating developmental trajectories from longitudinal data. Both mothers and fathers (N = 152 couples), with children ages 6-18 at the first wave, evaluated their relationship and parenting stress on up to 4 occasions over a 14-year period. The study provided separate models of change over time for mothers and fathers which showed that marital quality, coparenting, and parenting stress are dynamic relationship constructs that changed during the child’s development. Overall, marital quality was found to follow a curvilinear pattern, with declines when children were adolescents and increases as children entered young adulthood. Positive coparenting increased linearly over time for mothers and fathers, and negative coparenting declined linearly for mothers. With an emphasis on transition periods in the family life cycle, trajectories included indicators of the child’s development to allow for periods of discrete change in the trajectories based on the child’s entrance into adolescence and young adulthood. The child’s entrances into these developmental periods were associated with changes in levels of marital quality and coparenting for mothers only. Patterns for stress over time depended on the parent reporting, with mothers reporting decreases in parent and family problems over time and a quadratic trend for pessimism, with initial growth in reported pessimism followed by declines as the children exited adolescence. Fathers, however, did not report significant changes for parent and family problems and perceived increases in pessimism with time. The study also assessed how support in the marital and coparenting roles with time is associated with levels of parenting stress. Marital quality consistently predicted lower levels of parent and family problems for both parents, but findings for associations between marital quality and pessimism, and coparenting with both types of stress, varied depending on the parent reporting.