In this paper we consider some changes that the use of graphics calculators imposes on the assessment of calculus and mathematical modelling at an undergraduate level. For a student who is proficient in the use of a graphics calculator many standard questions involving differentiation, numerical integration or the graphing of functions do not necessarily test the mathematical skills traditionally regarded as fundamental. Furthermore, the use of a graphics calculator requires new skills to be acquired and employed effectively. Any assessment will therefore need to take into account such items as transcription skills, the limitations of the calculator and the student's ability to frame problems. We indicate some of the ways in which the assessment of mathematical tasks can be modified as the mechanics of calculation become routine and questions of analysis and interpretation assume greater importance. Particular references will be made throughout to the HP 38G and the HP 48G graphics calculators.