The study examined the effectiveness of Group Triple P, a Level 4 variant of the Triple P multilevel system of parenting support, with Chinese parents who had a preschool aged child with a developmental disability, using randomized controlled trial design. Participants (Intervention group: 42; Waitlist Control group: 39) completed measures on child behaviour, parental stress, dysfunctional discipline styles and parental conflict before and after program completion by the Intervention group. Intervention group participants also completed these same measures six months after program completion. Compared to the Waitlist Control group, parents receiving Group Triple P reported significantly lower levels of child behaviour problems, parental stress, dysfunctional discipline style and parental conflict scores. The Intervention group participants maintained their gains six months after program completion. The results provided promising evidence for the Level 4 Group Triple P as an effective intervention program for Chinese parents who have preschool aged children with developmental disabilities. (Contains 3 tables and 1 figure.)