This paper describes the development and psychometric evaluation of a parent and child report measure of life interference and impairment associated with childhood anxiety, the Child Anxiety Life Interference Scale (CALIS). The CALIS is designed to measure life interference and impairment experienced by the child from the child (9 items) and parent (16 items) point of view and also the interference experienced by the parent in their own life. A total of 622 children between 6 and 17 years of age, and their parents, completed the CALIS. Results indicated that the CALIS has good internal consistency, moderate-to-high test re-test reliability, significant inter rater reliability, good convergent and divergent validity and is sensitive to treatment change. The CALIS is a reliable and valid tool for the assessment of life interference and impairment associated with anxiety disorders in childhood.