  This work represent the first major study of the optical and IR
characteristics of the mass donor companions to the X-ray pulsars in the Small
Magellanic Cloud (SMC). In this work several new counterparts have been
identified, and possible ones confirmed, as companions to X-ray pulsars in the
SMC giving a total of 34 such objects now identified. In addition this work
presents three new binary periods and confirms two X-ray periods using optical
data for objects in this group. This homogeneous sample has been studied as a
group to determine important general characteristics that may offer insight
into the evolution of such systems. In particular, the spectral class
distribution shows a much greater agreement with those of isolated Be stars,
and appears to be in some disagreement with the galactic population of Be stars
in Be/X-ray binaries. Studies of the long term optical modulation of the Be
star companions reveal an extremely variable group of objects, a fact which
will almost certainly make a major contribution to the pronounced X-ray
variability. The spatial distribution of these systems within the SMC is
investigated and strongly suggests a link between massive star formation and
the HI density distribution. Finally, studies of the circumstellar disk
characteristics reveal a strong link with optical variability offering
important clues into the long-term stability of such disks.
