Neutron capture cross sections are averaged over Maxwell-Boltzmann neutron distributions for temperatures pertinent to slow nucleosynthesis ($s$ process) in red giant stars. Such cross sections, together with isotopic abundances, provide the major quantitative experimental tests of the theory. The cross sections are tabulated at convenient intervals from $kT=5$ keV to $kT=90$ keV where data are available. In many cases it has been possible to supplement the often fragmentary (as of June 1964) data with evidence from nuclear systematics.