The present study examines the expression of nominal reference in French Sign Language (LSF). We will show that an analysis of nominal reference in sign languages (SL) has to take into consideration not only lexical signs but also the constructions currently referred to as CLASSIFIER CONSTRUCTIONS in the literature (called NON-CONVENTIONAL UNITS in what follows to use a theory-neutral term). Non-conventional units have been identified in all studied SLs and have long been recognised in diverse theoretical approaches under different names. Nevertheless, the description and the analysis of these units remain a major topic of debate in SL literature. As shown below, the few studies of nominal reference in SLs do not take Non-conventional units into account. However, according to our study, nominal reference--and particularly the expression of definiteness and specificity--crucially require a better understanding of the interrelations between lexical signs and non-conventional units.