  We confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual
or spectroscopic companions of the beta Pictoris Moving Group (BPMG). Of these,
41 are new discoveries, increasing the known low-mass members by 45%. We also
add four objects to the 14 known with masses predicted to be less than 0.07
Msun. Our efficient photometric+kinematic selection process identified 104
low-mass candidates which we observed with ground-based spectroscopy. We
collected infrared observations of the latest spectral types (>M5) to search
for low gravity objects. These and all <M5 candidates were observed with
high-resolution optical spectrographs to measure the radial velocities and
youth indicators, such as lithium absorption and H-alpha emission, needed to
confirm BPMG membership, achieving a 63% confirmation rate. We also compiled
the most complete census of the BPMG membership with which we tested the
efficiency and false-membership assignments using our selection and
confirmation criteria. We assess a group age of 22 +/- 6 Myr using the new
census, consistent with past estimates. With the now densely sampled lithium
depletion boundary, we resolve the broadening of the boundary by either an age
spread or astrophysical influences on lithium burning rates. We find that 69%
of the now known members with AFGKM primaries are M stars, nearing the expected
value of 75%. However, the new IMF for the BPMG shows a deficit of 0.2-0.3 Msun
stars by a factor of approximately 2. We expect that the AFGK census of the
BPMG is also incomplete, probably due to biases of searches towards the nearest
stars.
