The development of object individuation, a fundamental ability that supports identification and discrimination of objects across discrete encounters, has been examined extensively by researchers. There are significant advancements in infants' ability to individuate objects during the first year‐and‐a‐half. Experimental work has established a timeline of object individuation abilities and revealed some mechanisms underlying this ability. However, the influence of adult assistance during object exploration has not yet been explored. The current study investigates the effect of adult involvement during object exploration on infants' object individuation abilities. In Experiment 1a and 1b, we examined 9.5‐month‐old infants' colour‐based object individuation following adult‐assisted multisensory object exploration. Two components of adult interaction were of particular interest: facilitation of object manipulation (grasping, rotating, and attention‐getting behaviours) and social engagement (smiling, pointing, attention‐getting verbalizations, and object‐directed gaze). Experiment 2a and 2b assessed these components with 4.5‐month‐olds to examine their impact across development. The results showed that after adult‐guided object exploration, both 9.5‐ and 4.5‐month‐old infants successfully individuated previously undifferentiated objects. Results of Experiments 1b and 2b provide implications for the mechanisms underlying the scaffolding influence of adult interaction during infant behaviours. Copyright © 2015 John Wiley & Sons, Ltd.