Although object-oriented languages such as Smalltalk do not seem very suitable for continuous simulation, they offer a set of characteristics and programming environments that are excellent for prototyping.This paper describes the previous author's experience developing continuous model simulation environments using FORTRAN and C programming languages and the current results obtained using Smalltalk. The transition from FORTRAN to C, from C to C++ and later on, the move to Smalltalk has been propelled by the need to develop more flexible and easy to use simulation environments.A continuous modeling and simulation environment has been implemented in the SmallTalk\V 286 system. The simulation environment , called SIMBIOS, strongly supports hierarchical modeling and simulation. In this system, users can examine their models in a highly flexible environment. Since interactive simulation is supported, the usual sequence of editing, translting, compiling, linking and simulating the model is avoided.