This study explores different aspects of the mapping between phonological form and meaning of signs in British Sign Language (BSL) by means of four tasks to measure meaning recognition, form recognition, form recall, and meaning recall. The aim was to investigate whether there is a hierarchy of difficulty for these tasks and, therefore, whether BSL vocabulary acquisition proceeds incrementally, as is the case for spoken languages. Twenty-four deaf participants (aged 5-15 years), all of whom were BSL users, performed with greatest accuracy on meaning recognition and least accurately on meaning recall. The results indicate that signers' knowledge of mapping between form and meaning in BSL signs is not an all-or-nothing phenomenon but depends on what the learner is required to do with that knowledge, as is the case for spoken languages. (Contains 11 notes and 6 tables.)