This study investigated ways to support young children's science, technology, engineering, and mathematics (STEM) learning and transfer of knowledge across informal learning experiences in a museum. Participants were 64 4- to 8-year-old children (Mage = 6.55 years, SD = 1.44) and their parents. Families were observed working together to solve one engineering problem, and then immediately afterward children worked on their own to solve a second engineering problem. At the outset of the problem-solving activities, families were randomly assigned to receive engineering instructions, transfer instructions, both engineering and transfer instructions, or no instructions. Families who received engineering instructions—either alone or in combination with the transfer instructions—demonstrated greater understanding and use of the engineering principle of bracing compared with those who received only transfer instructions. Moreover, older children who received both engineering and transfer instructions were more successful when working on their own to solve a perceptually different engineering problem compared with older children who received only one set of instructions or no instructions. Implications of the work for developmental and learning science research and informal education practice are discussed.