CUNY Transfer Explorer (CUNY T-Rex) was developed to simplify the transfer of credits and represents an at-scale technology tool solution that provides transparent and up-to-date information about transfer credit equivalencies to students, faculty, and advisors. In addition to collaborating with CUNY to develop CUNY T-Rex, ITHAKA S+R undertook a mixed-methods evaluation to understand the process, conditions, and business requirements that were involved in the launch and proliferation of CUNY T-Rex, as well as to understand the behaviors, uses, and implementation of CUNY T-Rex at individual institutions and system wide. This first of two reports examines the use and implementation of CUNY T-Rex and seeks to answer the following questions: (1) How do students use CUNY T-Rex? How might they use it more effectively? (2) How do college faculty and staff use CUNY T-Rex to support students? How might they use it more effectively? and (3) How has CUNY T-Rex been implemented across CUNY colleges? Results provide insights into the use cases and experiences of both stakeholders (institutional and system-wide) and students using CUNY T-Rex and the perspectives of institutional stakeholders regarding implementation of the tool across the CUNY system. The report provides: (1) background on the development of CUNY T-Rex and its core functionalities; (2) context of transfer activity within the CUNY system; and (3) information about what can be gleaned from website analytics about who is using CUNY T-Rex and which features they most commonly access.