  We present a comprehensive study of accretion activity in the most underdense
environments in the universe, the voids, based on the SDSS DR2 data. Based on
investigations of multiple void regions, we show that AGN's occurrence rate and
properties differ from those in walls. AGN are more common in voids than in
walls, but only among moderately luminous and massive galaxies (M_r < -20, log
M_*/M_sun < 10.5), and this enhancement is more pronounced for the weakly
accreting systems (i.e., L_[O III] < 10^39 erg/s). Void AGN hosted by
moderately massive and luminous galaxies are accreting at equal or lower rates
than their wall counterparts, show less obscuration than in walls, and
similarly aged stellar populations. The very few void AGN in massive bright
hosts accrete more strongly, are more obscured, and are associated with younger
stellar emission than wall AGN. Thus, accretion strength is probably connected
to the availability of fuel supply, and accretion and star-formation co-evolve
and rely on the same source of fuel. Nearest neighbor statistics indicate that
the weak accretion activity (LINER-like) is not influenced by the local
environment. However, H IIs, Seyferts, and Transition objects prefer more
grouped small scale structures, indicating that the rate at which galaxies
interact with each other affects their activity. These trends support a
potential H II -> Seyfert/Transition Object -> LINER evolutionary sequence that
we show is apparent in many properties of actively line-emitting galaxies, in
both voids and walls. The subtle differences between void and wall AGN might be
explained by a longer, less disturbed duty cycle of these systems in voids.
