Eclipse is a leading development environment that provides a rich set of features supporting Java development. However, little data is available about its usage: which features and plug-ins are developers using? Usage data from 41 developers using Java and Eclipse to support their daily work reveals that developers are using some advanced features, such as refactoring and third-party tools. However, they rarely use other features, such as bookmarking places in the code. Open source projects, such as Eclipse, should involve gathering and analyzing more usage data to ensure the tools evolve to meet the needs of their user communities.