The SPIRIT-Children and Adolescents (SPIRIT-C) 2026 statement is a new extension of the SPIRIT recommendations for pediatric randomized controlled trial (RCT) protocols in children and adolescents aged 0-19 years. A detailed protocol is essential to evaluate the aim, design, implementation, measurements, planned analyses, participant burden, and safety of the study for investigators, editors, funders, regulators, systematic reviewers, and stakeholders, including children, adolescents, and family caregivers. SPIRIT-C 2026 includes 17 new items recommended for reporting. Items are aligned with CONSORT-C 2026, the consolidated reporting standards for completed pediatric RCTs. It was developed in partnership with young people aged 10-24 and family carers under the SPIRC framework for improving the quality and transparency of health research. The aim is to improve the reporting and utility of pediatric RCT protocols.