We present a new measurement of the mass-concentration relation and the stellar-to-halo mass ratio over the halo-mass range 5 × 1012 to 2 × 1014 M . To achieve this, we use weak lensing measurements from the Canada-France-Hawaii Telescope Stripe 82 Survey (CS82), combined with the central galaxies from the redMaPPer cluster catalog and the LOWZ/CMASS galaxy sample of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data Release. The stacked lensing signals around these samples are modeled as a sum of contributions from the central galaxy, its dark matter halo, and the neighboring halos, as well as a term for possible centering errors. We measure the mass-concentration relation: with A = 5.24 1.24, B = −0.13 0.10 for 0.2 < z < 0.4, and A = 6.61 0.75, B = −0.15 0.05 for 0.4 < z < 0.6. These amplitudes and slopes are completely consistent with predictions from recent simulations. We also measure the stellar-to-halo mass ratio for our samples, and find results consistent with previous measurements from lensing and other techniques.