The project will conduct a series of user studies to investigate the effectiveness of error reporting with novice programming students. The studies will focus on how students understand error messages, the effectiveness of source-code highlighting, and the impact of language syntax on how students process errors. The PIs will instrument a programming environment to collect fine-grained data on how students respond to errors. Such scientific user studies, particularly at a fine-grained level, are rare in this context; the methodologies and tools developed for this project will be applicable to future studies. Study results will be used to improve programming environments for novice programmers with regards to interfaces for reporting errors and linguistic choices regarding syntax and type systems. Findings will identify principles for others who design new programming tools for novices. Results will be disseminated through the DrRacket environment, which is in wide use in introductory computing courses in universities, high schools, and after-school programs for middle school students.