Casting director Renee Rousselot searched over 1,000 small children for someone to portray Adam, the newest addition to the Szalinski clan. She searched for mostly three- to four-year-old boys because a younger child was thought to be problematic. She came across twins Daniel and Joshua Shalikar from New Jersey and immediately cast them in December 1990. One would act in the morning while the other was eating lunch or taking a nap. Baby consultant Elaine Hall Katz and director Randal Kleiser would plan the twins' scenes a week in advance. Tom Smith reported that, "On his own, Dan was almost too adventuresome to repeat one move, and Josh seemed very cautious. Put them together and they could do anything." However, the film did have difficulties in working with such small children, and one crew member later remarked it was "like playing hopscotch on hot coals".