The object mouthing of a developmentally delayed 8-year-old girl was assessed and treated in a classroom setting. Two pretreatment assessments were conducted: A functional analysis indicated that object mouthing occurred across test conditions and persisted in the absence of social contingencies, and assessment of stimulus preference identified reinforcers to be used during treatments. Based on assessment outcomes, two treatments were implemented. Noncontingent sensory reinforcement was implemented during free-time and group activities, resulting in a 74.3% decrease in object mouthing across three settings. During one-on-one educational activities, presentation of academic task-trials at a high rate decreased object mouthing by 85.7%, relative to a condition in which tasks were presented at a slower rate.