The grammaticai competence through the language assessment: Finnish as a foreign language in the school in St.Petersburg The article concerns the material, based on my investigation on the communicative competence of Russian-speaking Finnish learners in the secondary school of St.Petersburg. The investigation was the part of the international Finnish-Russian research project "Language and Education in Intercultural Integration", financed by the Academy of Finland and coordinated by the Centre for Applied Language Studies of the University of JyvaskyHi in 1996-2000. In the framework of the theoretical basis of L2 learning and acquisition, the structural model of communicative language competence (Canale, M. & Swain, M. 1980; Canale, M. 1983) consists of different components, one of which is grammatical competence. Actually, grammatical competence is reflected in other competences such as socio-linguistic competence (through lexical and idiomatic competence) and especially in discourse competence (through syntactical and textual competence). The group of Finnish learners (n = 30, grades 9-ll of Russian school, age 14-17 years) participated in the YKI (Yleiset kielitutkinnot) tests three times, in 1996, 1998 and 1999. My interest was focused on the skills in reading comprehension, writing, and structures and vocabulary. One of the most interesting questions was to find out the different components of communicative competence of young learners of Finnish from their performances in the tests. On the basis of the original analysis, the results showed that the eriticaI point for the learners in Finnish language acquisition was the integration of grammatical and sociolinguistic competences. Thus, the correct word form from the grammatical point of view can appear as semantic disharmony from the socio-linguistic perspective, which is dealt with as a mistake according to the YKI criteria. The culture-orientated content of the test tasks influences the selection of the proper word and structure. The detailed analysis of the performances and YKI's hidden curriculum of test tasks can be used in the practical work of teachers of Finnish as a foreign language in non-authentic contexts for getting information about learners' grammaticai and socio-linguistic competence.