Recent data from the WMAP, ACT and SPT experiments provide precise measurements of the cosmic microwave background temperature power spectrum over a wide range of angular scales. The combination of these observations is well fit by the standard, spatially flat ΛCDM cosmological model, constraining six free parameters to within a few percent. The scalar spectral index, n s=0.9690±0.0089, is less than unity at the 3.5σ level, consistent with simple models of inflation. The damping tail of the power spectrum at high resolution, combined with the amplitude of gravitational lensing measured by ACT and SPT, constrains the effective number of relativistic species to be Neff=3.28±0.40, in agreement with the standard model's three species of light neutrinos. © 2013 American Physical Society.