Background: Inadequate fruit and vegetable consumption is associated with increased chronic disease risk and represents a considerable global health burden. Despite evidence that dietary habits track from early childhood, there are few published trials of interventions attempting to increase preschoolers? fruit and vegetable consumption. Objective: The Healthy Habits trial aimed to assess the efficacy of a telephone-based intervention for parents to increase the fruit and vegetable consumption in their 3?5-y-old children. Design: A cluster randomized controlled trial was conducted involving 394 parents of children aged 3?5 y recruited through local preschools. Parents allocated to the intervention received printed resources plus four 30-min telephone calls targeting aspects of the home food environment associated with children s fruit and vegetable consumption. Parents allocated to the control group received generic printed nutrition information. Children s fruit and vegetable consumption was assessed by using the Fruit and Vegetable Subscale of the Children s Dietary Questionnaire, which was administered via telephone interview at baseline and 2 and 6 mo later. Results: Analysis of all available data showed that children s fruit and vegetable scores were significantly higher in the intervention group than in the control group at 2 mo (P <0.001) and at 6 mo (P = 0.021). Sensitivity analysis using baseline observation carried forward showed an intervention effect at 2 mo (P = 0.008) but not at 6 mo (P = 0.069). Conclusions: Telephone-delivered parent interventions may be an effective way of increasing children s fruit and vegetable consumption in the short term. Further investigation to determine whether the intervention effect is maintained in the longer term is recommended. This trial was registered at http://www.anzctr.org.au as ACTRN12609000820202.