This study identifies the development of information search expertise of 12 beginning research students (six in education and six in engineering) who were provided with a set of systematic search training sessions over a period of one year. The study adopts a longitudinal approach in investigating whether there were different stages in the development of search expertise for the research students, and examines the contributing factors in their progress from one stage of expertise to the next. The inclusion of both education and engineering students allows the researcher to examine whether search expertise development is different for students in different domains. This study provides a model which relates students' growth and development in research expertise to information search expertise. The results show that every student went through three stages of information needs during graduate studies, and the changes in information needs reflect the students' growth in knowledge of their subject. It was also found that the research students had problems in finding relevant information sources and that they needed to at least achieve a competent level of expertise in order to effectively locate information. (Contains 1 note and 1 figure.)