This paper describes and evaluates an action research project carried out by a teacher in an English comprehensive school, where a class of 13- to 14-year-olds was taught personal, social and health education and German through content-language integrated learning (CLIL) over a six-week period. The purpose of the study was to explore how CLIL would influence both motivation and attainment by giving learners the opportunity (i) to experience language learning with a broader, more applied purpose; (ii) to experience success in TL interactions; and (iii) to use linguistic structures in a more "natural" context. The findings of the study were mixed with regard to motivation, as pupils struggled to equate their continued lack of confidence after a short period of CLIL with their increased academic success. With regard to attainment, the most able pupils exceeded their previous achievements by at least one National Curriculum level, although little improvement was noted in the levels of the less able pupils. This could be attributed to the short time frame of the study, and the resulting lack of confidence referred to above. This research is also evidence of the developing role of practitioner-research in the academic community, the validity and importance of which is also discussed. (Contains 4 notes, 2 tables, and 1 figure.)