This study investigated the notions of washback and classroom-based assessment within the context of the "First Certificate of English (FCE)" examination and the students at the British Institute of Florence (BIF). A review of the literature examining classroom-based assessment revealed several limitations in previous research. This study examined the washback effects of a classroom-based assessment task on the language processing of two individual learners (i.e., one high-ability and one low-ability) studying at the BIF. The results suggested that the classroom assessment task had a differential impact on how the two learners processed the new learning point, impacting the accuracy and speed to which the new target language form was processed. The findings from the investigation suggested that there were distinct differences in student learning/processing at the individual level. (Contains 1 table and 3 figures.)