© 2015, BMJ Publishing Group. All rights reserved. Background: Paediatric dog bites are a significant public health problem worldwide. Existing prevention programmes focused on altering children’s risky behaviour with pet dogs tend to be atheoretical and only moderately effective.Objective: Test efficacy of a website to train young children in relevant cognitive skills to be safe with pet dogs in their home.Setting: Birmingham, Alabama, USA.Methods: A randomised trial will be conducted with an expected sample of two groups of 34 children (total N=68) ages 4–6 years. One group will engage in the newly designed website at home for 2 weeks and the other group will engage in a control website on transportation safety for an equivalent amount of time. All participants will complete a battery of laboratorybased tests to assess safety with dogs and cognitive functioning at baseline and postintervention. Outcome measures Primary analyses will be conducted through linear mixed models testing change over time. Children’s cognitive functioning, knowledge about safety with dogs, and behaviour with dogs in simulation and in vivo will serve as the primary outcomes.