The current project investigates native language teaching significance for bilingual students vocabulary development in both the mother tongue as a second language and exemplifies what it could mean to develop a school-related language simultaneously in two languages. Moreover examines the relationship between students' vocabulary development and their development of reading comprehension in two languages, which includes a focus on the relationship between the development of morphological awareness and reading comprehension. The study examines the mother tongue teaching role in the lexical development in the early school years, because we compare the development in Swedish and Somali for a group of Somali-Swedish speaking students who participate in school mother tongue teaching with that of a group of Somali-Swedish speaking students who are not in school mother tongue education . We follow a group of students from grades 1-2, and a group from grades 4-5. Our goal is to (1) compare the results of the groups on a series of tests that measure the breadth and depth of students 'vocabulary, both in the mother tongue Somali and other language Swedish, (2) discuss the relationship between students' vocabulary development and their early reading skills in both languages, which are examined using a series of tests that measure students 'ordavkodningsförmåga and reading comprehension in both languages, and (3) compare the groups' language development over time. The quantitative part of the study is supplemented with a qualitative study on mother tongue teaching in Somali and in the teaching of Swedish as a second language working with early reading and writing and the students' expansion of vocabulary. This is examined through participant observation of mother tongue education Somali and teaching in Swedish as a second language, which is carried out continuously for one year. In conversations with the teachers discussed how they see their teaching, the methods and materials they use and the way in which they consider that teaching can help students' language development. Teachers will be asked to comment videotaped sequences of teaching. The justification for the choice of the mother tongue education in Somalia is that the conditions of the Somali minority group in Sweden is calling explored, particularly in the school context, despite the fact that Somalia today is one of the ten most common mother tongues in Swedish primary school, according to recent statistics from the National Agency. Although we know today that the vocabulary is a very central component for students kunskapstillägnande are no previous studies have investigated the role of mother tongue education has been for this, as it is organized in Sweden today. Too few previous studies focused relationship between bilingual students' vocabulary development and their development of reading comprehension. Additionally focuses many previous studies of bilingual children's vocabulary development too narrowly on only one aspect of the children's vocabulary development, eg only how many words they can or only one of the children's language (most often the majority language / school language). Thus miss the opportunity to get a holistic view of students 'lexical skills and see how development proceeds in parallel in the students' two languages. In the present study, we therefore include several measures of students' lexical breadth and depth that we connect to their performance on several measures of reading comprehension. All tests performed on both the students' first language Somali and their second language Swedish. The study represents a measure morphological awareness (of several) of the students' lexical deep, because on the basis of studies of monolingual children were able to see that morphological awareness is of great importance both for the development of the technical side of the reading as the reading comprehension. Finally, the current project contribute to a deeper knowledge of the mother tongue teaching design and content, which is missing in the Swedish context.