Developmental disabilities in children alter the children’s life and that of the family. Parents of children with disabilities may experience positive or negative beliefs and thoughts regarding disabilities of their children that adversely impact parenting practices, children's adjustment, and families' adjustment. Aim of the study was to assess illness cognition and family adjustment among parents of children with disabilities attending speech clinics and rehabilitation centers. Subjects and Methods: A descriptive cross-sectional study was conducted including 80 parents of children with disabilities attending Speech Therapy Clinics affiliated to Zagazig University Hospitals and El-Ahrar Hospital. In addition to The Center of Rehabilitation affiliated to Faculty of Disability Science and Rehabilitation, Zagazig University, Egypt. Tools: Four tools were used to collect data. Tool I: An Interview sheet for demographic data of the studied parents and their children, as well as medical diagnosis of children. Tool II: The Illness Cognition Questionnaire Parent-version. Tool III: The Child Adjustment and Parent Efficacy Scale-Developmental Disability. Tool IV: The Parenting and Family Adjustment Scale. Results: The results showed that 52.5% of parents had low level of illness cognition and poor efficacy to adjust their children’s problems, and 73.8% of parents practiced low level of parenting and family adjustment. However, 65.0% of parents practiced low parental consistency and 63.7% practiced high coercive. Conclusion: Parents showed low level of illness cognition regarding their children's disability with less acceptance, less perceived benefits, and more helplessness. Children with disabilities have emotional, behavioral and prosocial problems with low adjustment and low parental efficacy. Parents practiced low level of parenting and family adjustment with low consistency and high coercive. Recommendations: The present study recommended that family-based interventions should be introduced by medical, psychological, and educational professionals as an urgent need for parents and all family members to help empower raising a child with a disability.