Objective: To develop an instrument to identify the challenges faced by faculty while implementing an integrated curriculum in an undergraduate dentistry program. Methods: The study was conducted between September 2020 and October 2021 at the University College of Medicine and Dentistry (UCMD), University of Lahore (UOL). A preliminary questionnaire, developed through literature review and faculty interviews was sent to 10 medical education experts for content validation via the Delphi technique. Content Validity Index (CVI) was calculated for individual items (I-CVI) as well as for the composite scale (S-CVI). A panel agreement of more than 75% was considered as the criterion for the inclusion of items in the questionnaire. Cognitive pretesting of five faculty members was conducted and pilot testing was subsequently done with 27 faculty members. The reliability of the tool was determined by Cronbach’s alpha. Results: After the Delphi process, the final Integrated Curriculum Implementation Challenges (ICIC) questionnaire had 42 items. S-CVI was 0.87 and the cut-off value for I-CVI was taken as 0.78 as the criterion for item deletion. Cognitive interviews and pretesting revealed good item interpretation. Cronbach’s alpha for this tool was 0.87. Conclusion: ICIC is a useful instrument with good reliability and content validity. It can be used to identify the presence and extent of challenges faced by the faculty while implementing an integrated curriculum. doi: https://doi.org/10.12669/pjms.40.1.7258 How to cite this: Aslam K, Khan RA, Aslam MA, Zaidi FZ. Curriculum implementation challenges: Development and validation of an integrated curriculum implementation challenges tool. Pak J Med Sci. 2024;40(1):---------. doi: https://doi.org/10.12669/pjms.40.1.7258 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.