  We will review our recent analysis of the magnetic properties of the O9IV
star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at
the Canada-France-Hawaii telescope within the context of the Magnetism in
Massive Stars (MiMeS) Large Program. We discuss our most recent determination
of the rotational period from longitudinal magnetic field measurements and
H_alpha variability - the latter obtained from over a decade's worth of
professional and amateur spectroscopic observations. Lastly, we report on our
investigation of the magnetic field geometry and the effects of the field on
the circumstellar environment.
