Mock (simulated) interviews can be used as a safe context for trainee interviewers to learn and practice questioning skills. When mock interviews are designed to reflect the body of scientific evidence on how questioning skills are best learned, research has demonstrated that interviewers acquire relevant and enduring skills. Despite the importance of this exercise in learning interview skill and its prevalence as a learning tool in other fields such as medicine and allied health, there has been relatively little discussion about mock interviews from an educational perspective in investigative interview training. This paper addresses that gap by providing the first comprehensive overview of the way mock interviews have been used in training interviewers of children. We describe the research that supports their utility, and the various ways they can be implemented in training: providing insight to learners; allowing opportunities for practice, feedback, and discussion; and as a standardized way to assess skill change over time. The paper also includes an overview of the cutting-edge use of avatars in mock interviews to enhance efficiency, provide unique learning experiences, and ultimately reduce training costs. We explain why avatars may be particularly useful in basic training, freeing up human trainers to facilitate mock interviews around advanced topics and discussion.