As the ultimate realisation of the phonological rules of a linguistic system, pronunciation in a foreign language represents an outer yet salient layer of one’s language proficiency, which is highly susceptible to cross-linguistic influences, in particular when multiple languages are involved. In cases of Hungarian secondary grammar school students, the route that second language acquisition (SLA) and third language acquisition (TLA) take is quite characteristic as two foreign languages (L2 and L3) are learnt simultaneously following the acquisition of L1. The interactions between these languages are manifold due to the fact that not only does L1 influence L2 and L3, but also the latter ones may have a mutual effect on each other (Jessner, 2006). In addition, several influential criteria, e.g. typological similarity, cultural similarity, level of proficiency, frequency of use and status, must also be considered when examining their interference. The specific languages subjected to scrutiny are Hungarian (L1), English (L2/L3), German (L2/L3) and French (L3), which represent both genetic (Indo-European vs. Uralic language) and phonological (true voice vs. spread glottis languages) differences. In order to determine participants’ linguistic background, which forms the basis for their categorisation, a profile questionnaire is set up that focuses on their age, gender, length of study of L2 and L3, age of language learning (LL) onset L2 and L3, the frequency of L2 and L3 lessons and possibly the duration and frequency of private lessons. Exposure to L2 and L3 according to students’ timetable is also expected to trigger a priming effect. As an initial stage of the diagnostic assessment process, identical extracts of contemporary literature are presented to the participants in their respective languages. By having them read out the texts, a comparatively controlled environment ensures the validity of the findings. Results of the piloting period enables the modification of the scheme as well as launching less controlled steps of assessment, i.e. topic-related free speech and complete spontaneous speech. Students’ performances are recorded, transcribed and analysed so that commonalities can be pinpointed.