  A rare opportunity to distinguish internal and environmental effects on
galaxy evolution is afforded by "Supergroups", systems which are rich and
massive but include several comparably rich substructures, surrounded by
filaments. We present here a multiwavelength photometric and spectroscopic
study of the galaxy population in the Supergroup Abell 1882 at $z$=0.139,
combining new data from the MMT and Hectospec with archival results from the
Galaxy And Mass Assembly (GAMA) survey, the Sloan Digital Sky Survey (SDSS),
NED, the Gemini Multi-Object Spectrograph (GMOS) and Galaxy Evolution Explorer
(GALEX). These provide spectroscopic classifications for 526 member galaxies,
across wide ranges of local density and velocity dispersion. We identify three
prominent filaments along which galaxies seem to be entering the Supergroup
(mostly in E-W directions). Abell 1882 has a well-populated red sequence,
containing most galaxies with stellar mass $>$ $10^{10.5}$ $M_{sun}$, and a
pronounced color-density relation even within its substructures. Thus, galaxy
evolution responds to the external environment as strongly in these unrelaxed
systems as we find in rich and relaxed clusters. From these data, local density
remains the primary factor with a secondary role for distance from the inferred
center of the entire structure's potential well. Effects on star formation, as
traced by optical and near-UV colors, depend on galaxy mass. We see changes in
lower-mass galaxies (M $<$ $10^{10.5}$ $M_{sun}$) at four times the virial
radius of major substructures, while the more massive $NUV$ Green Valley
galaxies show low levels of star formation within two virial radii. Suppression
of star formation ("quenching") occurs in the infall regions of these
structures even before galaxies enter the denser group environment.
