Volume One focuses on the quality of life (Qol) of those with intellectual disabilities, commencing with a systematic review of established Qol measures to identify how these measures have been utilised and the factors that have been explored. In the resulting papers, environmental factors were considered more frequently than individual characteristics. Further research is needed for the continued development of Qol measures in order to provide services with a pragmatic way of documenting change and encourage continued focus on the individual. The empirical paper focuses on the health related quality of life (HrQol) of individuals with rare genetic disorders (Angelman, Cornelia de Lange and Cri du Chat syndromes). The variable of health, HrQol and level of challenging behaviour (CB) was explored. Individuals were found to have a high prevalence of health problems, which in turn was associated with lower HrQol. Understanding the progression of health problems and the impact in those with intellectual disabilities can aid early recognition and treatment. Volume Two contains five clinical practice reports including a service evaluation, case study and single case experiment. The reports cover a range of disorders and theoretic approaches and provide details of assessment, formulation, treatment, evaluation and reflections.