It is well established that not all investigative interviewers adhere to ‘best-practice’ interview guidelines (i.e., the use of open-ended questions) when interviewing child witnesses about abuse. However, little research has examined the sub skills associated with open question usage. In this article, we examined the association between investigative interviewers' ability to identify various types of questions and adherence to open-ended questions in a standardized mock interview. Study 1, incorporating 27 trainee police interviewers, revealed positive associations between open-ended question usage and two tasks; a recognition task where trainees used a structured protocol to guide their response and a recall task where they generated examples of open-ended questions from memory. In Study 2, incorporating a more heterogeneous sample of 40 professionals and a different training format and range of tests, positive relationships between interviewers' identification of questions and adherence to best-practice interviewing was consistently revealed. A measure of interviewer knowledge about what constitutes best-practice investigative (as opposed to knowledge of question types) showed no association with interviewer performance. The implications of these findings for interviewer training programs are discussed.