More than 60% of the nation's 14 million community college students are required to complete at least one developmental mathematics class before enrolling in college-credit courses; however, 80% of them do not successfully complete any college-level mathematics course within 3 years. To address this problem, the Community College Pathways initiative was launched in 2009. A core element is the Pathways Faculty Support Program, professional development aimed at supporting faculty to develop knowledge, beliefs, skills, and practices for teaching Pathways courses. In fall 2014, a redesign of the program used improvement science methods to design an infrastructure for responsive, flexible professional development that is sensitive to varying and changing conditions, with mechanisms for identifying, designing, and testing ideas for improvement. Specifically, our team employed a user-centered design process that foregrounds the needs and work processes of Pathways faculty and a measurement system that drives the continuous improvement of the program.