Environmental attitude covers a person's behavioural aims, impacts, and believings which is acquired from environmental subjects or activities. It is also mentioned that environmental attitude can be used in order to predict environmental behaviour. The aim of this study is to analyse the efficiency of an ecopedagogy-based TUBITAK environmental education project, which comprised of community of practice and was titled "Ecology in Canakkale and Around, 2010", on environmental attitude of in-service teachers and to determine whether there is any difference between genders in terms of environmental attitude. The methodology of the study was mixed methodology within a case study. The qualitative and the quantitative data were collected simultaneously and evaluated together. An environmental attitude scale was used in order to collect the quantitative data. The participants' diaries, semi-structured interview and nonparticipant observation notes were used in order to collect the qualitative data. It was found that the ecopedagogy-based environmental education caused to change environmental attitude of in-service teachers favourably and this change was observed mostly on male in-service teachers.