Purpose: This study's purpose was to develop a better understanding of the experiences of parents of children with achondroplasia and to provide qualitative evidence to support the development of a patient-reported outcome (PRO) measure of parent impacts.Methods: Concept elicitation (CE) individual/focus group interviews were conducted with parents of children aged 2 to < 12 years with achondroplasia in the United States and Spain. The qualitative analysis informed the PRO measure development. Cognitive debriefing (CD) interviews were conducted to ensure parent understanding and item relevance.Results: Thirty-six parents participated in individual/focus group CE interviews. The analysis identified parent impacts in four domains, including caretaking responsibilities, emotional well-being, family, and work, and results informed the development of the Achondroplasia Parent Experience Measure (APEM). Caretaking responsibilities included managing child's medical care (92%), helping child with self-care (67%), advocating for child (64%), assisting child (56%), and observing/monitoring child (e.g., to ensure safety; 47%). Impacts on parents' emotional well-being included worry about the future (75%), worry about child's physical health (67%), safety concerns (50%), feeling stressed/overwhelmed (44%), and worry about child's social relationships (42%). Impacts on family and work included family strain (56%), limiting/adapting family activities (42%), and missed work time (50%). CD interviews with an additional 16 parents of children with achondroplasia confirmed understanding and item relevance.Conclusion: The results improve our understanding of the experiences of parents of children with achondroplasia and provide qualitative evidence to support the content validity of the APEM. A psychometric study is needed to validate the measure. [ABSTRACT FROM AUTHOR]