This project utilizes an innovative technique involving observations of Zeeman-broadened optical and infrared absorption lines to measure the magnetic field strength and active region 'filling factor' on the surfaces of young T Tauri stars. Spectrophotometry is also used to quantify the temporal variation and complex geometry of the surface fields. These observations will provide strong constraints on current stellar 'turbulent dynamo models' for the origin and pervasiveness of magnetic activity on young T Tauri stars. They also are also likely to lead to significant improvements in understanding the magnetic connection between the inner boundary of accretion disks and young stellar photospheres.
