OBJECTIVE: To test the efficacy of Hand Arm Bimanual Intensive Therapy Including Lower Extremity (HABIT-ILE) to improve gross motor function, manual ability, goal performance, walking endurance, mobility, and self-care for children with bilateral cerebral palsy (CP). STUDY DESIGN: This prospective, waitlist randomized controlled trial included children with bilateral CP, aged 6-to-16-years and classified Gross Motor Function Classification System (GMFCS) levels II to IV. HABIT-ILE delivered for 2 weeks (65 hours) was compared with usual care (UC). Primary outcomes post-intervention were gross motor function (Gross Motor Function Measure-66) and manual ability (ABILHAND-Kids). Secondary outcomes were goal performance (Canadian Occupational Performance Measure), self-care and mobility (Pediatric Evaluation of Disability Inventory-Computer Adapted Test), bimanual hand performance (Both Hands Assessment), and walking endurance (6 Minute Walk Test). Linear regression models were used to determine between group differences, adjusted for baseline scores. RESULTS: 92 children were recruited; two were deemed ineligible after randomization and were excluded. 90 children (HABIT-ILE n=46, UC n=44), mean age 10.4 (SD 3.0) years, GMFCS II=32; III=31; IV=27 were included. HABIT-ILE led to superior gains in manual ability (mean difference 0.85, 95% CI 0.38-1.33; P<0.001) but not gross motor function. HABIT-ILE led to superior changes on goal performance, self-care, and mobility. CONCLUSIONS: HABIT-ILE was effective in improving manual ability, mobility, self-care, and goal performance, but not gross motor function. Significant gains immediately post-intervention were retained at 26 weeks. Large individual variability suggests further analyses need to be performed to understand characteristics of children who achieved clinically meaningful gains across outcomes.