Purpose: This study investigated the early rule-based sentence productions of 3- and 4-year-old children with severe speech disorders who used single-meaning graphic symbols to communicate. Method: Ten 3- and 4-year-olds requiring the use of augmentative and alternative communication, who had largely intact receptive language skills, received instruction in producing up to four different semantic-syntactic targets using an Apple iPad with a communication app. A single-case, multiple-probe, across-targets design was used to assess the progress of each participant and target. Generalization to new vocabulary was assessed, and a subgroup also was taught to produce sentences using grammatical markers. Results: Some targets (primarily possessor-entity) were mastered in the baseline phase, and the majority of the remaining targets were mastered during intervention. All four children who completed intervention for grammatical markers quickly learned to use the markers accurately. Conclusions: Expressive language potential for preschoolers using graphic symbol-based augmentative and alternative communication systems should not be underestimated. With appropriate presentation and intervention techniques, some preschoolers with profound speech disorders can readily learn to produce rule-based messages via graphic symbols.