This study examined the relationship among grandparent support, family functioning, and parental stress on families with children with and without disabilities between the ages of 2 and 12 years. Families are viewed as an ever-changing complex system with reciprocal interactions. One possible stressor on the family system is the birth of a child with a disability. Parenting stress levels seem to fluctuate in the family system over time depending on the age of the child with a disability, developmental stage, and demands of the age and stage. Studies show that social support, specifically that from grandmothers, can buffer some of the stress related to parenting a child with a disability (Kuster & Merkle, 2003; Mitchell, 2007; Trute, 2003). The current study addressed the following research questions: (1) Do families with a child with a disability differ from families without a disabled child with regard to grandmother support, family functioning, and parental stress? (2) What are the relationships among grandmother support, family functioning, and parental stress in families with a child with a disability? Fifty-three mother-grandmother dyads completed surveys regarding their support, parent stress, child stress, life stress, family cohesion, and family flexibility. Results for the current study revealed that the groups were comparable on most family demographic variables, such as mother age, grandmother age, ethnicity, and highest level of education. Significant differences were observed in the ages of the target child and annual income between groups. Significant differences were also observed between groups with regard to overall stress, parenting stress, and child stress. Total stress, parent stress, and child stress were higher in families with a child with a disability than in families with a child without a disability. Grandmother support was positively associated with family flexibility and inversely related to life stress. Grandmother support abated some stress related to major life events and enhanced family flexibility. Support from grandmothers did not, however, enhance family cohesion or reduce stress related to raising a child with a disability. In sum, the experience of parenting stress, child stress, and overall stress was higher in families with a child with a disability, and grandmother support was associated with reduced life stress and enhanced family flexibility; however, grandmother support was not found to enhance family cohesion, or diminish parenting stress, child stress, or overall stress experienced by mothers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]