Despite controversy in the literature, the present article assumes that the adult learning theory provides a powerful framework for evaluating training practices. This study explores the degree to which adult learning traits are embedded in optional seminars, the primary form of formal in-service teacher training in Cyprus and a traditional, structural approach towards teacher development. A quantitative research design is employed, with a nationally representative number of participants. Teachers' views indicate adult learning as multidimensional, with the emerging factor structure similar to that derived from relevant literature, as to the extraction of the factors: orientation to learning, readiness to learn, accumulated experience and self-concept. Two additional factors -organization of seminars and dissemination of results -show that these two dimensions should also be taken into consideration in training design. Although teachers' views about optional seminars appear predominantly positive, such optimistic outcomes should not be projected in uncritical ways since positive attitudes could be attributed to the voluntary character of participation and the subconscious application of adult learning strategies by trainers. Despite such limitations, possible action should focus, among others, on training the trainers, restructuring organizational aspects as well as enhancing dissemination practices.