Object technology is finally making inroads into scientific programming. In this talk we will cover four areas in which this technology is being brought to bear on the problems of creating large scientific simulations:

• Expression template technology enables Fortran-speed code that is nevertheless highly abstract.
• Object design can make mathematical libraries much more usable.
• Object-based Fortran can bring some of the benefits of the object revolution to the Fortran programmer.
• Steering using an object-oriented scripting language is creating "plug and play" architectures for scientific programs, responding to the growing pressures for omnibus models and rapid response to business opportunities.