Environmental education promotes the use of higher-order thinking skills, encourages informal experiences in school as well as outdoors and brings together children and adults in order to make a contribution to the environment. Its holistic nature, that encompasses various subject matters, learning environments and teaching methods and encourages cognitive, affective and behavioural outcomes, requires the implementation of an appropriate assessment framework. In this study the author introduced a complex assessment method that encompasses pre, in- and after-course assessments and incorporates instruments that assess knowledge, reasoning, decision-making and the active involvement of 27 senior pre-service science and technology teachers who participated in an environmental education course. Findings indicate that the multiple assessment modes employed expressed a wide range of learning in the course. The team investigation project was found to be most suitable for developing environmental awareness, as well as inquiry skills. Self and peer assessment enhanced critical thinking and continuous discussion. The students acknowledged the complex assessment method as a possible model for an assessment framework which corresponds to the unique nature of learning in environmental education. The assessment framework introduced included aspects of environmental knowledge as well as awareness, skills, attitudes, values and practical involvement and addressed most of the courses basic ideas and components.