The objective of this nationwide (i.e., England), longitudinal (i.e., 2015-2024), and commissioned (i.e., National Disability Sport Organisation) study was to co-produce research with and for disabled children and young people with limb difference and their families to encourage participation in physical activity and create a more equitable and socially just society. Underpinned and informed by an equitable and experientially informed form of co-production, a core working group (N=45) was formed of families, service providers, and academics. Two research aims were constructed: (a) identify and understand a timely, relevant, and meaningful barrier to physical participation experienced by children and young people with limb difference and their families in England; and (b) co-produce resources that address this barrier and encourage physical activity participation. Multiple methods of data collection were used (N=4 multistakeholder sandpits; 84 meetings; N=351 nationwide surveys, N=26 focus groups, N=22 interviews). The barrier– ‘The Knowledge Gap’ (i.e., informational knowhow, experiential knowhow, and practical knowhow)– was addressed through three co-produced resources: website, social media forum, and physical activity events. Given a recent national survey in England found that disabled children are less active than their non-disabled peer (Activity Alliance 2020, 2024) and the World Health’s Organisation’s (2019) global action plan on physical activity, we believe this research makes a significant contribution to national and international strategy.