ASCEND is an equation solver and interactive mathematical modelling system for engineering and science problems. Tracks units of measurement, solves steady and dynamic (NLA, ODE, DAE) problems. ASCEND IV is both a large-scale object-oriented mathematical modeling environment and a strongly typed mathematical modeling language. Although ASCEND has primarily been developed by Chemical Engineers, great care has been exercised to assure that it is domain independent. ASCEND can support simulation activities in fields from Architecture to (computational) Zoology.