Objective: Intrathecal baclofen treatment is used for the treatment of dystonia in patients with severe dyskinetic cerebral palsy; however, the current level of evidence for the effect is low. The primary aim of this study was to provide evidence for the effect of intrathecal baclofen treatment on individual goals in patients with severe dyskinetic cerebral palsy. Methods: This multicenter, randomized, double-blind, placebo-controlled trial was performed at 2 university medical centers in the Netherlands. Patients with severe dyskinetic cerebral palsy (Gross Motor Functioning Classification System level IV–V) aged 4 to 24 years who were eligible for intrathecal baclofen were included. Patients were assigned by block randomization (2:2) for treatment with intrathecal baclofen or placebo for 3 months via an implanted microinfusion pump. The primary outcome was goal attainment scaling of individual treatment goals (GAS T score). A linear regression model was used for statistical analysis with study site as a covariate. Safety analyses were done for number and type of (serious) adverse events. Results: Thirty-six patients were recruited from January 1, 2013, to March 31, 2018. Data for final analysis were available for 17 patients in the intrathecal baclofen group and 16 in the placebo group. Mean (standard deviation) GAS T score at 3 months was 38.9 (13.2) for intrathecal baclofen and 21.0 (4.6) for placebo (regression coefficient = 17.8, 95% confidence interval = 10.4-25.0, p < 0.001). Number and types of (serious) adverse events were similar between groups. Interpretation: Intrathecal baclofen treatment is superior to placebo in achieving treatment goals in patients with severe dyskinetic cerebral palsy. ANN NEUROL 2019.