Kenya's language-in-education policy supports mother-tongue education as the ideal approach to developing language and literacy skills of young learners. The policy has been informed by findings of various past national education commissions as well as international declarations such as the UNESCO declaration on the use of Vernacular Languages in Education of 1953, the World Declaration on Education for All of 1990 and the Dakar framework of 2000. The country's Constitution of 2010 re-affirms this policy. However, available reports indicate that little progress has been made in implementing the use of Kenyan mother tongues in education. This paper reports on impressions gained in the process of collecting and analysing data for a doctoral study still in progress. Preliminary findings indicate that in most urban and peri-urban schools, where the learner population is highly multilingual, the policy has been implemented in such a way that in effect either the notion of "mother tongue" seems to have been redefined or the term is used in an unconventional way. Even in rural areas where, comparatively, there is minimal diversity, practical aspects of the use of mother tongue in education seem not to be in accordance with policy provisions. Learning materials and assessment systems are not suitably structured to enable mother-tongue education to take place. The paper (1) gives an impression of the status quo regarding use of language in multilingual primary school classrooms in Kenya, (2) considers the different interpretations given to the term "mother tongue" in current classroom practices and (3) provides pointers to the gap between "de jure" and "de facto" policy, which may eventually be helpful in improving the implementation of the current language-in-education policy, in such a way that it will strengthen mother-tongue literacy and facilitate eventual transfer to English as medium of instruction. (Contains 4 notes and 5 excerpts.)