The detrimental effects of children’s anxiety during anesthesia induction are welldocumented. Though pharmacological approaches (e.g., sedative) are efficacious, they have potential negative consequences. As such, non-pharmacological approaches (e.g., parental presence, anesthetic mask exposure) may be preferable. Recent research has demonstrated the utility of a parent-directed intervention involving exposure to the anesthetic mask in increasing child compliance and decreasing anxiety at anesthetic induction. In the mentioned study, anesthetic mask exposure occurred on the day of surgery, and employing the mask exposure intervention earlier may be beneficial. The current randomized control trial examined the efficacy of parent/guardian-directed anesthetic mask exposure and shaping practice for the prevention of child preoperative anxiety, with a specific focus on the timing of exposure. Participants included children (n = 110) ages 4 to 7 years undergoing a day surgery dental procedure and their parents/guardians. Families were randomly assigned to one of three groups: (1) parent/guardian-directed anesthesia mask exposure/shaping practice at least three times in the week prior to surgery (Group 1); (2) parent/guardian-directed anesthesia mask exposure/shaping practice at least once on the morning of surgery (Group 2); (3) no exposure to the anesthesia mask prior to anesthetic induction (Group 3). The primary outcome measure was child anxiety which was observer-rated at five time points (admission, holding area, transfer to OR, anesthetic induction, and post-surgery) using the modified Yale Preoperative Anxiety Scale. Results demonstrated significant differences in observer-rated child anxiety at anesthetic induction across groups. Specifically, Group 2 demonstrated significantly lower observer-rated anxiety than Group 3 with a medium effect. A significant interaction was observed between these two groups over time (i.e., admission to anesthesia induction). Group 2 also demonstrated the best anesthesia induction compliance (i.e., significantly lower scores than Group 3). The current results suggest that the timing of the delivery of anesthesia mask exposure (i.e., on the day of surgery) as an intervention to address preoperative anxiety in children, at least in the day surgery setting of this investigation, may be an important consideration. The current results inform the integration of this simple, cost-effective strategy into clinical practice.