We perform a joint analysis of the auto and cross-correlations between three cosmic fields: the galaxy density field, the galaxy weak lensing shear field, and the cosmic microwave background (CMB) weak lensing convergence field. These three fields are measured using roughly 1300 sq. deg. of overlapping optical imaging data from first year observations of the Dark Energy Survey and millimeter-wave observations of the CMB from both the South Pole Telescope Sunyaev-Zel'dovich survey and Planck. We present cosmological constraints from the joint analysis of the two-point correlation functions between galaxy density and galaxy shear with CMB lensing. We test for consistency between these measurements and the DES-only two-point function measurements, finding no evidence for inconsistency in the context of flat ΛCDM cosmological models. Performing a joint analysis of five of the possible correlation functions between these fields (excluding only the CMB lensing autospectrum) yields S_8≡σ_8√(Ω_ m/0.3) = 0.782^+0.019_-0.025 and Ω_ m=0.260^+0.029_-0.019. We test for consistency between these five correlation function measurements and the Planck-only measurement of the CMB lensing autospectrum, again finding no evidence for inconsistency in the context of flat ΛCDM models. Combining constraints from all six two-point functions yields S_8=0.776^+0.014_-0.021 and Ω_ m= 0.271^+0.022_-0.016. These results provide a powerful test and confirmation of the results from the first year DES joint-probes analysis.
