Current thinking in language teacher education emphasises the importance of the development of teachers' practical knowledge. However, while several studies have focused on describing practical knowledge in different contexts, there has been less research conducted into the manner in which practical knowledge develops in the context of in-service teacher education and into the factors that influence such development. These issues are addressed in this paper, which explores how three teachers of English on an in-service BA Teaching English to Speakers of Other Languages programme in the Middle East grew in practical knowledge, specifically with regard to the design and use of communicative tasks. Using qualitative data, the article charts their development over 3 years, examining changes in their ideas and practices. Implications for in-service language teacher education are discussed.