Berger worked at Argonne National Laboratory as a scientific programmer after graduating from SUNY.
Her specific duties included developing models for the Energy and Environmental Systems Division.
After graduating with her Ph.D., she began working at the Courant Institute of Mathematical Sciences at New York University, first as a postdoc, then as a faculty member.
[5] Berger has pioneered the technique of adaptive mesh refinement which is used in the numerical solution of systems of partial differential equations (PDEs).
Berger is also known for contributions to Cartesian mesh finite difference methods for numerical PDE's.