When an adolescent has chronic pain many aspects of a parent’s life can be affected, including their emotional and social functioning. The assessment of this multidimensional parental impact is an essential, yet often neglected, clinical task. This study reports on the development and psychometric evaluation of the Bath Adolescent Pain–Parental Impact Questionnaire (BAP-PIQ), an assessment tool comprising multiple scales thought to be relevant for better understanding changes in functioning and behavior associated with parenting an adolescent with chronic pain. A sample of 194 parents of adolescents with chronic pain, recruited from three UK clinics, completed the 94 item draft inventory. Frequency and item correlation analyses resulted in a final inventory of 62 items. Internal consistency of all eight scales was established based on Cronbach’s alpha. Convergent validity was undertaken by comparison of individual scales with existing validated measures of parental stress, mood, parenting behavior, marital adjustment, and general functioning. The temporal reliability of each scale was established using a sub-sample of 46 participants over a 14-day period. Psychometric evaluation suggests that the inventory yields a reliable and valid assessment of the multiple impacts of parenting an adolescent with chronic pain. The BAP-PIQ may offer a comprehensive assessment of these impacts in both a research and a clinical setting. Further study of the validity of BAP-PIQ scales and their ability to detect clinically meaningful change would be of use. Additional data from samples comprising fathers of adolescents with chronic pain and parents of adolescents with non-musculoskeletal pain would be of benefit.