UML class diagrams of complex software systems are frequently very large, making it difficult to gain a detailed understanding of the underlying software components within the context of the overall software system. To overcome this limitation, we apply focus + context visualization techniques to an interactive UML browser. We display software components at varying levels of detail according to a dynamic degree of interest function. We then lay out the diagram components to maximize space efficiency while emphasizing the relationships between components. Preliminary results of our work are presented here.