In this study, the prototype of a new type of bilingual picture book was field-tested with two sets of mother-son subject pairs. This picture book was designed as a possible tool for providing children with comprehensible input during their critical period for second language acquisition. Context is provided by visual cues and both Japanese and English (the target language) are used in the story, providing enough information for a child to be able to follow the story regardless of English proficiency level. The two mothers were asked to read the picture book to their children on a regular basis over the course of a month and to take notes on their children's reactions. The children's knowledge of target vocabulary was tested both before and after the trail. Results showed that while the children had no difficulty following the story or acquiring language by this method, the mothers were initially skeptical. This suggests that the greatest obstacle to using these materials for second language learning may lie in educating teachers and parents in how to use them and convincing them of the material's efficacy.