Review article 70 Rasku-Puttonen, H., et al. 2004. Developing teachers’ professional expertise through collaboration in an innovative ICT-based learning environment. European Journal of Teacher Education, 27 (1), 47-60. This article aims to find out how teachers develop their practical knowledge and expertise through shared planning and to evaluate an innovative learning project carried out in an ICT-based environment. The participants were two secondary school teachers with history as their specialty. Two classes from separate schools shared an ICT-based learning environment where 34 students (aged 13) carried out a five month history learning project. Teacher-student and student-student interactions were videotaped throughout the project. The teachers’ classroom talk was recorded using a wireless microphone. Both whole class processes and small group interactions were videotaped. This study is mainly based on analyses of the data collected by interviewing the teachers three times during the study. Findings of the study reveal that the teachers spent more time on planning their instruction for the history project than was required for other lessons. The teachers report that before the lessons they searched relevant data banks, web pages and other appropriate information sources and knowledge bases for material for the students. While instructing their students the teachers had to reflect continuously on their learning and teaching activities. Collaboration makes it possible for teachers to establish more personal contact with their students and to monitor the strategies these apply during learning activities. The teachers participating in the study judged that ICT enhanced the motivation of their students. The study indicates that teachers’ reflection on their practices might result in increased awareness of their own practices, shared planning and evaluation of the teaching-learning process created an appropriate context for teachers’ professional learning. The authors argue that teachers need personal experience with the use of information and communication technologies if the use of information and communication technologies if they are to make them an essential component of the learning environment. Keywords: ICT based learning environment; Collaboration; Secondary education; History project; Shared planning.