Background: There is very little published research regarding the experiences and perceptions of parents of children with a diagnosis of Attention Deficit Hyperactivity Disorder (ADHD), particularly in relation to their child's grandparents. There is no empirical material available which explores how grandparents perceive ADHD symptomology, assessment, treatment or support, and very little is written about the roles, influences or contributions of non-custodial grandparents in the lives of children with ADHD and their families. Aims: This study investigates how parents and grandparents perceive ADHD symptomology, causality, assessment, treatment and support. This includes the questions, how do parents perceive the influence of grandparents upon the child and how do grandparents themselves perceive their own influence? The study also considers how differences in perception between parents and grandparents may affect family relationships, symptomology and outcomes relating to treatment. Methods: A Mixed methodology is employed. Quantitative analysis compared the ratings from 56 parents and 31 grandparents of child strengths and difficulties, effects upon family life and grandparent support. Qualitative Interpretive Phenomenological Analysis (IPA) of semi-structured interviews, withl6 birthmother and maternal grandmother dyads demonstrated the importance of this relationship. Results: Significant differences were found between parental and grandparental ratings. IPA produced sixteen superordinate themes relating to the birthmother and maternal grandmother dyads, organised within four overarching themes: Causes and contributory factors; Experiences of assessment, treatment and support; Pains and pleasures of relationships relating to child; and maternal grandmother's roles and influences. Conclusions: Grandparents, particularly maternal grandmothers, often play a crucial role for families of children with ADHD. An intergenerational perspective and the involvement of grandparents relating to assessment and treatment processes can make a crucial contribution to diagnostic practices and contribute towards enhanced well-being for children with ADHD and their families. Recommendations are made and clinical approaches, methods and techniques are illustrated in highlighting how this can be achieved Declarations of interest and responsibility: No interests to declare. The information and analysis presented within this thesis are the sole responsibility of the author. The copyright of this thesis rests with the author and no quotations or information derived from it may be published without their prior written permission