We have been investigating the design, development and evaluation of modeling and database systems (MDBS) that support the iterative, data-intensive and numerically-intensive modeling activities of scientists involved in large-scale earth science investigations. Based on intensive studies of particular applications, we have developed architecture for MDBS that is based on a model of scientific activity that we constructed. We have designed comprehensive data and metadata models (``lattice of representational domains''), a language (modeling and database language) and distributed database support that are well-suited for scientific modeling activities. We have constructed and evaluated a ``proof-of-concept'' prototype and arecurrently building a second prototype that is being used to solve significant scientific problems. To date, over 25 papers have been published concerning this research.