The challenges of learning academic language for students learning English as a second language has been the focus of much attention in education in the past decade. Many studies have looked at different instructional methods and their effects on children's literacy development. However, few have looked at how teaching specific grammatical features in the context of different academic genres affects the writing development of children learning English as a second language. This study presents an analysis of the effects of explicit instruction on children's use of genre specific features in academic writing. Grammar features of narrative and expository genres were explicitly taught in the context of their use in texts to fourth and fifth grade English Learner students. The instructional cycle included building background knowledge of the topic, explicitly teaching, highlighting and analyzing specific grammatical features in context, activities that allowed for practice and use of the language features of the genre, co-construction of a text of the genre, and independent writing. Growth of writing development was measured by collecting and analyzing pre-instruction and post-instruction writing samples of both genres for length, frequency of use of a number of grammatical features, and overall organization and development. The analysis found that the overall length of texts increased significantly for both genres in the post-instruction writing samples. In addition, students used genre appropriate language, developed more complex character descriptions and plots, and incorporated more dialogue in the narrative post-instruction texts. The analysis also found that students' use of causal connectives, nominalization, and descriptive language increased in expository post-instruction writing. The organization and development of topics also showed growth in the expository post-instruction writing. These findings suggest that explicit instruction of genre specific grammatical features in context does have an effect on the writing development of children learning English as a second language. The findings of this study have several pedagogical implications for teachers. Teachers need to have an understanding of and familiarity with the features of different genres, raise awareness and explicitly teach the grammatical features of academic genres, engage students in practice and use of the language, and reflect on instruction and student writing.