Two groups of police investigators were trained in the use of the National Institute of Child Health and Human Development (NICHD) interview protocol. After the training, one group (n = 8) received written feedback on each interview they conducted, whereas the other group (n = 11) did not. The objective of the study was, first, to evaluate the effect of NICHD protocol implementation on the types of questions and details provided by children and, second, to evaluate the impact of post-training feedback. Interviewees were alleged sexual abuse victims between the ages of 3 and 14 years. Application of the NICHD protocol allowed interviewers to use more open-ended questions and to obtain more details. The results show that providing feedback significantly increased the quality of the interviews. It is recommended that the NICHD protocol be used to interview child victims and witnesses and that feedback sessions be held with interviewers. Copyright © 2012 John Wiley & Sons, Ltd.