Designing a flexible grid enabled scientific modeling interface. The Espresso Scientific Modeling Interface (Espresso) is a scientific model productivity tool developed for climate modelers. Espresso was designed to be an extensible interface to both scientific models and Grid resources. It also aims to be a contemporary piece of software that relies on’s Java CoG Kit for a Grid toolkit, Sun’s Java 2 API and is configured using XML. This article covers the design and implementation of Espresso’s Grid functionality and how it interacts with existing scientific models. We give specific examples of how we have designed Espresso to perform climate simulations using the PSU/NCAR MM5 atmospheric model. Plans to incorporate the CCSM and FOAM climate models are also discussed.