In an article that discussed both the conceptual aspects of presence and the practical considerations of measuring the concept (Witmer & Singer, 1998), we argued that both involvement and immersion are necessary for experiencing presence. The article also presented two questionnaires we have developed, an Immersive Tendencies Questionnaire (ITQ) and a Presence Questionnaire (PQ). Our analyses showed that they are internally consistent with high reliability, there is a weak but consistent positive relation between presence and performance, the ITQ predicts presence as measured by the PQ, and individuals reporting more simulator sickness symptoms report less presence than those reporting fewer symptoms. In this issue, Slater (1999) critiques our approach to measuring presence as represented by the PQ. Dr. Slater finds our definitions of presence helpful and that our concept of immersion is part of his understanding of the meaning of presence. Dr. Slater then argues that both our approach to measuring presence and the PQ are conceptually flawed. In his critique, he raises statistical questions about our measure, concluding that the PQ is not a measure of presence at all. He concludes by arguing against the validity of the measure and stating that he would not use the PQ in his research. In this article, we argue that the PQ is based in the same conceptual structure that is accepted by Dr. Slater, and that the PQ represents a fundamentally sound approach—although not the only approach—to measuring presence. Dr. Slater's statistical arguments are shown to be incorrect simplifications, as he acknowledges in his critique. We also demonstrate that individual PQ items still correlate significantly with the PQ total score even when the PQ total is adjusted to remove the score on individual items from that total. Finally, we rebut Slater's argument concerning the validity of the measure, and suggest that researchers not be constrained by an equipment-oriented model of the presence experience.