This study debates an intervention programme for kindergarten and school teachers' continuing education in Germany that aims at biases against language outside a perceived monolingual ‘standard’ and its speakers. The programme combines anti‐bias methods linked to linguistic diversity with aims of increasing critical language awareness. Assessment via teachers' workshops in Berlin and Brandenburg indicates positive and enduring attitudinal changes in participants, but not in control groups that did not attend workshops, and effects were independent of personal variables gender and teaching subject and only faintly linked to age. The study links these effects to such programme features as indirect and inclusive methods that promote active engagement, and the combination of ‘safer’ topics targeting attitudes towards linguistic structures with more challenging ones handling the discrimination of speakers.