This report explores the potential effects of microcomputers and hand-held calculators on mathematics and science curricula in secondary school and the first year of college. The potential effects of these technologies on curricula are likely to occur in two areas: content and delivery. Calls for change in curricular content appear focused on mathematics where the major effect of technology may be to shift the focus of instruction from manipulative to higher order skills. Modifications in curricular delivery are evident in both mathematics and science. Trends include the use of computers and calculators to (1) demonstrate concepts, (2) teach content through experimentation, and (3) teach content through programming. The implications of these potential changes for achievement testing include threats to test validity and credibility. Threats to validity arise primarily from the potential mismatch between test and curricular content. Threats to credibility are linked to the perception that programs that ignore technology are out-of-date and to the view that tests dictate curricula. Research to address these threats is suggested.