How children acquire a sign language and the stages of sign language development are extremely important topics in sign linguistics and deaf education, with studies in this field enabling assessment of an individual child's communicative skills in comparison to others. In order to do research in this area it is important to use the right methodological tools. The contributions to this volume address issues covering the basics of doing sign acquisition research, the use of assessment tools, problems of transcription, analyzing narratives and carrying out interaction studies. It serves as an ideal reference source for any researcher or student of sign languages who is planning to do such work. This volume was originally published as a Special Issue of <i>Sign Language & Linguistics</i> 8:1/2 (2005)