Pedro Szekely has spent his entire professional career working to make computers more useful and easier to use. This has led him to make contributions in many areas in computer science. In human-computer interaction he pioneered model-based techniques to generate easy-to-use interfaces from simple, high-level specifications, contributing to reducing the cost for implementing user-interface software. In visualization he developed tools to easily generate sophisticated visualizations of complex data, focusing on time-oriented data. In data-query he developed techniques to enable casual users to easily ask complex questions using metaphors that hide queries from users and enables them to focus on their data. In multi-agent systems, he developed algorithms to enable distributed teams of people to coordinate their activities, lowering the risks and pitfalls of coordination breakdowns. In planning and scheduling he developed algorithms and user interfaces to easily adapt their plans during execution to cope with disruptions in dynamic environments.