Review article 69 Leach, Jenny. et al. 2004. Deep impact: A study of the use of hand-held computers for teacher professional development in primary schools in the global South. European Journal of Teacher Education, 27 (1), 5-28. This article is related to the Digital Education Enhancement Project (DEEP), which is investigating the ways in which new technologies can improve the teaching of literacy, numeracy and science in primary schools in Egypt and South Africa. Forty-eight primary teachers (24 in each country) have been carrying out a sequence of classroom-focused professional development activities, using a range of new technologies. Each teacher has been provided with a hand-held computer and pocket camera for use throughout the project. This study reports on the use made of these devices by teachers and students over a 12-month period. The data drawn on include pre-and post-project questionnaires and teacher interviews, together with observations of teachers and students using the hand-held computers. The findings of the study indicate that use of the hand-held computers has: i) enhanced teacher professional capability by widening opportunities for professional planning; extending their range of pedagogic practices and subject knowledge; and permitting new forms teacher-to-teacher cooperation; ii) improved teacher professional development in relation to the way students view their teachers; the way local communities perceive the school; and teachers’ aspirations for future personal development and iii) varied in relation to context, particularly with respect to teacher access to adjacent technologies; geographical location; local educational and cultural practices; and home language. The study suggests that future research and development should exploit the potential for improvement and the conditions in which such outcomes can be realized, and further investigate the potential of state of the art technologies for contributing to teacher education in developing contexts. Keywords: Hand-held computers; Pocket camera; Primary school; Professional practices; Pedagogy; Literacy; Numeracy; Science; Egypt; South Africa.