Background: Advances in modern medicine and a proliferation of high-quality research focused on the prevention, diagnosis and early intervention for children with Cerebral Palsy (CP) have led to remarkable declines in the incidence and severity of CP in high income countries over the past decade. The result is less children are being born with CP and the severity of motor impairments and associated conditions are decreasing. There is, however, more work to be done to develop safe and effective rehabilitative interventions for children living with CP who are marginally ambulant or non-ambulant (Gross Motor Function Classification Scale (GMFCS) levels III-V). Some children with CP experience declining gross motor function as they transition from childhood to adolescence, resulting in the loss of ability to perform sit-to-stand (STS) transfers, ambulate or participate in leisure activities. Goal-directed training approaches to improve gross motor function in children with CP are substantiated by high quality evidence, with a strong focus on ambulant children (GMFCS I-III). Adapted cycling is part of a burgeoning area of interest for healthcare workers who are committed to finding safe and inclusive modes of exercise for children with CP across all GMFCS levels. It can be difficult, however, for some children to self-propel on an adapted bike, and the efficacy of cycling to improve gross motor function is unclear. Functional Electrical Stimulation (FES) cycling is a novel technology that may provide opportunities for children with CP to strengthen their lower limbs, improve functional independence and increase their capacity to cycle on an adapted bike in the community. In light of the scarcity of evidence-based rehabilitative interventions appropriate for both ambulant and non-ambulant children with CP, a program of goal-directed training, FES-cycling and adapted cycling was developed. Aim: This doctoral program aimed to: (i) determine the efficacy of cycling-based interventions to improve functional outcomes in children aged 2-18 years (GMFCS levels I-V); (ii) design an intervention of goal-directed training, FES-cycling and adapted cycling based on current evidence (Activate-CP); (iii) test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in children with CP compared to usual care; (iv) determine if functional improvements gained during Activate-CP training could be retained, eight weeks after completing the training, and (v) explore the experiences of participants and parents in the Activate-CP training program. Methods: A systematic review and meta-analysis was completed to inform the development of Activate-CP: an eight-week program of goal-directed training, FES-cycling and adapted cycling. A waitlist randomized controlled trial (RCT) protocol was designed and implemented to test the efficacy of Activate-CP to improve gross motor function, goal performance and satisfaction in ambulant and non-ambulant children with CP (GMFCS II-IV), aged 6-18 years old. Participants were randomized to the intervention group (n=11) who commenced Activate-CP training immediately, or a waitlist control group (n=10). Outcomes were assessed at baseline, post-training and at eight-weeks post-training (follow-up). Primary outcomes were gross motor function assessed by the Gross Motor Function Measure (GMFM) and goal performance/satisfaction assessed by the Canadian Occupational Performance Measure (COPM). Secondary outcome measures included the five times sit-to-stand test (FTSTS), Pediatric Evaluation of Disability Index (PEDI-CAT), Participation and Environment Measure-Children and Youth (PEM-CY) and cycling power output and resistance. Pre-training, post-training and follow-up data from both groups were pooled to investigate retention of effects at eight-weeks follow-up. Semi-structured interviews were conducted at the end of Activate-CP and a thematic analysis undertaken to explore participant’s experiences. Results: A systematic review identified nine studies (N=282) on cycling interventions for children with CP and suggested that cycling may improve muscle strength (effect size (ES): 0.77-0.93), cardiorespiratory function (ES: 1.13-1.77) and gross motor function (ES: 0.91) in children with CP. Studies were limited by small sample sizes and a lack of follow-up testing and focused predominantly on stationary cycling among ambulant children. The Activate-CP RCT was designed, developed, and delivered to 21 participants (intervention group n=11; waitlist group n=10). The intervention group had significant and clinically meaningful improvements on the GMFM (MD=7.7, 95% CI 2.3-12.6; p=0.007), COPM (MD=4.4; 95% CI 3.9-5.3; p<0.001;ES=3.32), and peak cycling resistance (MD=3.4; 95% CI 1.0-5.8; p=0.009) immediately post-training compared to the waitlist group. There were no significant between-group differences immediately post-training on secondary outcomes. Participants retained meaningful improvements on the GMFM and COPM that were higher than baseline values at eight-weeks follow up. Improvements in cycling power output and resistance, PEDICAT daily activities, PEMCY environmental barriers and FTSTS were also retained at follow-up. A thematic analysis of 17 interviews with participants (n=11) and their carers’ (n=18) revealed four major themes: facilitators and challenges to program engagement; perceived outcomes; the FES-cycling experience; and previous cycling participation. Conclusion: Activate-CP was effective to improve gross motor function, goal performance and satisfaction and peak cycling resistance in ambulant and non-ambulant children with CP, and improvements were retained in the short term. Findings reported in this thesis support Activate-CP as a new and alternative intervention to improve functional outcomes in children with CP. Facilitators and challenges to participant engagement were identified and hold practical relevance for clinicians who work with children with CP who have goals to improve functional independence or cycling. Environmental and personal factors should be carefully considered when developing future rehabilitation programs for ambulant and non-ambulant children with CP, to maximise opportunities for success.