This paper reports the findings of a two-year design study exploring instructional conditions supporting emerging, bilingual/biliterate, four-year-olds' digital composing. With adult support, children used child-friendly, digital cameras and iPads equipped with writing, drawing and bookmaking apps to compose multimodal, multilingual eBooks containing photos, child-produced drawings, writing and voice recordings. Children took digital cameras home, and home photos were loaded onto the iPads for bookmaking. In Year 1, eBook activities successfully supported children's multimodal composing. Children used similar writing forms on the page and screen, and explored the keyboard as an option for writing. Children used digital images as anchors for conversation and composing, and produced oral recordings extending and elaborating written messages. However, most dual-language recordings were created by Spanish-English bilinguals, with speakers of other languages rarely composing in their heritage languages. In Year 2, we redesigned eBook events to better support all children as multimodal, multilingual composers. Revised eBook activities included multilingual, demonstration eBooks containing all the children's languages, with translations by bilingual adults known to the children. Beginning early in the school year, these eBooks were publicly shared in large group activities. The results showed that all emergent bilingual/biliterate children created dual-language recordings for their eBooks in Year 2. We concluded that: (a) the ability to integrate photos and voice recordings with print and drawings provided new opportunities for learning and teaching not available in page-based composing; (b) the affordances of iPads for children's learning were shaped by local language and literacy practices.