We investigated how change in the characteristics of 140 adolescents and young adults with an autism spectrum disorder (ASD) would predict subsequent change in maternal well-being and in the quality of the mother-child relationship. Overall patterns of improvement in maternal well-being and mother-child relationship quality were observed during the study. When the son or daughter had declining behavior problems, were prescribed more psychotropic medications, and exited from high school during the study period, mothers' well-being and perception of relationship quality improved to a greater extent. In addition, improvements in maternal well-being and relationship quality were observed in mothers of daughters, in mothers of individuals with mental retardation as well as ASD, and in mothers of those in better health.