We present here 350 and 500 micron polarization observations of the Lupus I molecular cloud taken during the 2010 BLASTPol Antarctic flight. Lupus I is a nearby, isolated, young, and filamentary molecular cloud making it an ideal target to test magnetically regulated star formation models. In the presence of intermediate to strong magnetic fields (in comparison to turbulence), these models predict the formation of large filaments extended perpendicular to the local magnetic field direction as gas preferentially collapses along the field lines. We compare the BLASTPol polarization observations with previous optical polarimetry and find a uniform large-scale field direction from low to high density in Lupus I, consistent with magnetically regulated star formation models.