The National Student Clearinghouse Research Center reports on the shifting transfer landscape during COVID-19 in a rapid response report series titled "COVID-19 Transfer, Mobility, and Progress." Two reports are issued per academic term, starting with a first look of the term, followed by the end of term update. As the fourth in the series, this edition is an end-of-term report for spring 2021. It focuses on year-over-year changes within a fixed panel of institutions that represent 94 percent of the Clearinghouse universe of institutions and 11.3 million undergraduate students (including 737,000 transfer students) reported as of April 22. As the effects of the pandemic continue to impact postsecondary institutions into late spring 2021, this research series attempts to quantify how the transfer and enrollment gaps by student characteristics that existed before the pandemic continue to be affected by these disruptions. Even before the pandemic, many college students intending to transfer struggled to manage the complexities of the transfer process, particularly those in underrepresented groups. The general dampening of student mobility during the pandemic that was first reported last fall (see ED609850) appears to continue into this spring. However, upward transfers from two-year to four-year institutions have weathered the effects of the pandemic better than all other pathways. This trend may be a reflection of ongoing efforts to streamline the transfer process during the pandemic in order to reduce inequities in access to bachelor's degrees. The data shows, however, that not all student groups have been able to leverage these opportunities. [For "COVID-19 Transfer, Mobility, and Progress: First Look Spring 2021 Report. Third in the Series," see ED613207.]