This dissertation is the result of studies concerning the prerequisites for Finnish to survive in contemporary Sweden. When the Sweden Finnish parents want instruction in Finnish for their children the only choice available in Swedish municipal schools is between two language programs: one giving instruction in Swedish classes with 1-2 hours of home language training in Finnish per week, and the other giving instruction in and of Finnish in Finnish classes. In a four part study I investigate whether Sweden Finnish pupils who take part in these programs use and have a command of both languages. The focus of the dissertation is nonetheless on Finnish and the possibilities for Sweden Finns to preserve and develop their language and culture. A total of 560 second generation Sweden Finns from Botkyrka participated in the studies and are divided by language programs into Finnish classes (273) and Swedish classes (287). The introduction of the dissertation gives a picture of the composition of the Sweden Finnish group, cultural aspirations and education possibilities. It also discusses the official position of the Swedish authorities as well as their efforts in relation to the Sweden Finnish aspirations. For comparison 411 Finland Swedish pupils from Turku as well as monolingual control groups in Finland and Sweden are also investigated. Questionnaires, tests, and essays were collected on two occasions, in 1980 and 1995. Command of reading and writing skills in Finnish and Swedish are compared among the Sweden Finnish, the Finland Swedish, and the monolingual pupils. The most bilingual were the Finland Swedish pupils. This group achieved better results on the Swedish tests than the other groups. On the Finnish tests they were better than the Sweden Finnish pupils in the Swedish classes. Compared to the Sweden Finnish pupils in Finnish classes, the Finland Swedish pupils read just as well or better but wrote less well. In the studies the Sweden Finnish pupils' language use in school and at home and the changes which had taken place during the fifteen years which had passed between the times of data collection were scrutinized. Compared to the Sweden Finnish pupils in Swedish classes in 1980 the Sweden Finnish pupils use much more Swedish today (1995) while the Sweden Finnish pupils in Finnish classes nowadays use both languages more often than those who took part in the same language program in 1980. In one study 41 former Sweden Finnish informants with an average age of 27 were re-visited. Those who had been in the Swedish classes tended to let Swedish take over at home while those who had been in the Finnish classes used both languages. Sixteen of the former informants had children of their own. The language chosen to use when speaking to their children correlated with their own language skills and the language of their partner. None of those who had been in the Swedish classes spoke Finnish with their children. Among those who were in Finnish classes various combinations of languages were applied: 40% spoke Finnish, 25% spoke both languages and 33% spoke Swedish. Nearly 90% of those who had been in Finnish classes wanted their children to learn Finnish in school while not quite 60% of those who took part in home language training wanted their children to learn Finnish in school. Judging from the results of the study, attendance in Finnish classes was of great significance for the preservation of Finnish in Sweden because only this program seemed to guarantee many-sided language skills in Finnish. The number of pupils in Finnish classes has decreased sharply since 1980, and nowadays such classes exist only in a few places in Sweden. Swedish school political practices have contributed strongly to the difficulties Finnish is having and will have surviving beyond the coming two or three generations.