This National Science Foundation (NSF) Project Grant award under the Computer and Information Science and Engineering (CFDA 47.070) program provides $647,993 to Carnegie Mellon University to strengthen the correctness of date and time computations in software systems. The 3-year project aims to systematically study past software bugs related to date and time calculations, and then develop techniques to automatically uncover new date and time-related errors in existing software. The research will result in materials to improve software engineering courses, as well as provide research opportunities for undergraduate and underrepresented students. The project seeks to enhance formal reasoning of date-based constraints and improve the reliability of critical software systems that rely on accurate date and time calculations.