Purpose: Non-rhotic varieties of English often use /?/ insertion as a connected speech process to separate heterosyllabic V1.V2 hiatus contexts. However, there has been little research on children's development of this strategy. This study investigated whether children use /?/ insertion and, if so, whether hiatus-breaking /?/ can be considered planned, as evidenced by F3 lowering on V1. Method: Thirteen Australian English-speaking children (7 girls, 6 boys; mean age 6;1 [years;months]) participated in an elicited production task. The stimuli included carrier sentences containing 4 test words (linking /?/ context: "door", "floor"; intrusive /?/ context: "paw", "claw") followed by of (e.g., "This is the 'paw' of the cat"). After familiarization containing auditory and picture prompts, children produced test sentences upon presentation of picture prompts alone. Results: Eight children produced /?/ insertion; the others used (some) glottalization. The incidence of /?/ did not vary across linking or intrusive contexts, and inserted /?/ was associated with F3 lowering at V1 onset relative to control items without /?/. Conclusion: Six-year-old Australian English-speaking children who use /?/ insertion show evidence of planning ahead and inserting /?/ as a segment. The implications for the development of speech-planning processes and phonological and lexical representations are discussed.