This study investigated teachers' perceptions and practices concerning musical improvisation in the English primary classroom. A questionnaire survey was carried out with participants drawn from primary teachers--both generalists and specialists--working in various regions of England. The findings demonstrate a positive view of teachers' perceptions and practices towards improvisation, with 81% of the teachers using improvisation in their music teaching. Teachers use improvisation mainly on their own initiative, whereas teachers who do not use improvisation lack personal involvement in improvisatory activities. The most usual ways of using improvisation are as a response to a visual, verbal or audio stimulus and as a means of showing emotions, themes, moods and ideas. Statistical analysis revealed significant associations between some factors--teachers' age, experience, professional qualifications, educational background--and teachers' practice regarding the use of improvisation. Teachers are more likely to use improvisation if they are older and/or more experienced, if they have a teaching qualification, and if their higher education included improvisation. Descriptive analysis of the data also explored teachers' personal observations and beliefs regarding the effects of improvisation, and the relationship between their teaching practice and the National Curriculum for music. (Contains 4 figures.)