  We report on a programme to monitor the radial velocities of a sample of
candidate and confirmed carbon-enhanced, metal-poor (CEMP) stars. We observed
45 targets using the Echelle Spectrographs of three 4m class telescopes. Radial
velocities for these objects were calculated by cross-correlation of their
spectra with the spectrum of HD 140283, and have errors < 1 km/s. Sixteen of
our programme's targets have reported carbon excess, and nine of these objects
also exhibit s-process enhancements (CEMP-s). We combine these stars' radial
velocities with other literature studies in search of binarity. The search
reveals that four of our CEMP-s stars (44%) are in binary systems. Using the
analysis of Lucatello et al. (2004), we find that all the CEMP-s stars in our
sample are binaries. This conclusion implies that CEMP-s stars may be the very
metal-poor relatives of CH and Ba II stars, which are believed to have acquired
their peculiar abundance patterns by mass transfer from a thermally-pulsing AGB
companion.
