American Sign Language (ASL) has become increasingly popular as a second language option at universities and colleges in North America. While a growing number of hearing, adult learners are enrolling in ASL classes, this has not been paralleled (yet) by an equal development in ASL research. There has been insufficient investigation into what constitutes ASL proficiency development and how proficiency can be validly and reliably assessed for this group of learners. This mixed-methods study explores the ASL program at a Canadian university. It investigates the construct of proficiency from
three angles: instructors' understanding and definitions of ASL proficiency; how student proficiency is determined through current assessment practices and; student responses to assessment practices. Results of this study suggest that in this context ASL proficiency is not clearly defined. Without a clear construct definition, what current ASL assessments are actually measuring is unknown, and consequently may not be providing valid results.