Research into the effect of phonetic complexity on phonological acquisition has a long history in spoken languages. This paper considers the effect of phonetics on phonological development in a signed language. We report on an experiment in which nonword-repetition methodology was adapted so as to examine in a systematic way how phonetic complexity in two phonological parameters of signed languages — handshape and movement — affects the perception and articulation of signs. Ninety-one Deaf children aged 3–11 acquiring British Sign Language (BSL) and 46 hearing nonsigners aged 6–11 repeated a set of 40 nonsense signs. For Deaf children, repetition accuracy improved with age, correlated with wider BSL abilities, and was lowest for signs that were phonetically complex. Repetition accuracy was correlated with fine motor skills for the youngest children. Despite their lower repetition accuracy, the hearing group were similarly affected by phonetic complexity, suggesting that common visual and motoric factors are at play when processing linguistic information in the visuo-gestural modality.

Given the current lack of appropriate assessment tools for measuring deaf children's sign language skills, many test developers have used existing tests of other sign languages as templates to measure the sign language used by deaf people in their country. This article discusses factors that may influence the adaptation of assessment tests from one natural sign language to another. Two tests which have been adapted for several other sign languages are focused upon: the Test for American Sign Language and the British Sign Language Receptive Skills Test. A brief description is given of each test as well as insights from ongoing adaptations of these tests for other sign languages. The problems reported in these adaptations were found to be grounded in linguistic and cultural differences, which need to be considered for future test adaptations. Other reported shortcomings of test adaptation are related to the question of how well psychometric measures transfer from one instrument to another.

The development of valid and reliable assessment tools to measure the acquisition of natural signed languages is of practical as well as theoretical significance. A selection of tests are described that are currently available or under development to assess several signed languages (American Sign Language, British Sign Language, German Sign Language, and Swiss German Sign Language) at the phonological, lexical, grammatical, and discourse levels. In addition to test descriptions, issues pertaining to test development procedures, test formats, normative sample composition, and the use of Web-based technology is discussed. The importance of assessment in guiding instruction in deaf education is emphasized throughout.