We assemble and observe a sample of poor galaxy systems that is suitable fo
r testing N-body simulations of hierarchical clustering and other dynamical
halo models. We (1) determine the parameters of the density profile rho(r)
and the velocity dispersion profile sigma(p)(R), (2) separate emission-lin
e galaxies from absorption-line galaxies, examining the model parameters an
d as a function of spectroscopic type, and (3) for the best-behaved subsamp
le, constrain the velocity anisotropy parameter, beta, which determines the
shapes of the galaxy orbits. Our sample consists of 20 systems, 12 of whic
h have extended X-ray emission in the ROSAT All-Sky Survey. We measure the
877 optical spectra of galaxies brighter than m(R) approximate to 15.4 with
in 1.5 h(-1) Mpc of the system centers (we take H-0 = 100 h km s(-1) Mpc(-1
)). Thus, we sample the system membership to a radius typically three times
larger than other recent optical group surveys. The average system populat
ion is 30 galaxies, and the average line-of-sight velocity dispersion is ap
proximate to 300 km s(-1). The Navarro, Frenk, & White universal profile an
d the Hernquist model both provide good descriptions of the spatial data. I
n most cases an isothermal sphere is ruled out. Systems with declining sigm
a(p)(R) are well-matched by theoretical profiles in which the star-forming
galaxies have predominantly radial orbits (beta > 0); many of these galaxie
s are probably falling in for the first time. There is significant evidence
for spatial segregation of the spectroscopic classes regardless of sigma(p
)(R).