  We present observational constraints on the galaxy-halo connection, focusing
particularly on galaxy assembly bias, from a novel combination of
counts-in-cylinders statistics, $P(N_{\rm{CIC}})$, with the standard
measurements of the projected two-point correlation function,
$w_{\rm{p}}(r_{\rm{p}})$, and number density, $n_{\rm{gal}}$, of galaxies. We
measure $n_{\rm{gal}}$, $w_{\rm{p}}(r_{\rm{p}})$ and $P(N_{\rm{CIC}})$ for
volume-limited, luminosity-threshold samples of galaxies selected from SDSS
DR7, and use them to constrain halo occupation distribution (HOD) models,
including a model in which galaxy occupation depends upon a secondary halo
property, namely halo concentration. We detect significant positive central
assembly bias for the $M_r<-20.0$ and $M_r<-19.5$ samples. Central galaxies
preferentially reside within haloes of high concentration at fixed mass.
Positive central assembly bias is also favoured in the $M_r<-20.5$ and
$M_r<-19.0$ samples. We find no evidence of central assembly bias in the
$M_r<-21.0$ sample. We observe only a marginal preference for negative
satellite assembly bias in the $M_r<-20.0$ and $M_r<-19.0$ samples, and
non-zero satellite assembly bias is not indicated in other samples. Our
findings underscore the necessity of accounting for galaxy assembly bias when
interpreting galaxy survey data, and demonstrate the potential of count
statistics in extracting information from the spatial distribution of galaxies,
which could be applied to both galaxy-halo connection studies and cosmological
analyses.
