Julia Hartmann is the Fay R. and Eugene L. Langberg Professor in Mathematics specializing in algebra and arithmetic geometry, a newer field that applies techniques from algebraic geometry to solve problems in number theory. With colleague David Harbater, Hartmann developed the method of field patching, which has expanded the ways mathematicians can analyze the relationships between local and global behaviors of mathematical objects. Moreover, field patching has recently led to the solution of a longstanding conjecture concerning the symmetry groups of differential equations. Hartmann serves as faculty sponsor of Penn’s chapter of the Association for Women in Mathematics and co-organizes GeMs in Math, a group of grad students, postdocs, faculty, and visitors in Penn’s Math Department who identify as gender minorities—and everyone who is an ally.