Using polarized reflectivity measurements of single-domain crystals, we are able to distinguish chain and plane contributions to the infrared conductivity of YBa2Cu3O7. A substantial chain contribution to persisting to low frequency and temperature is observed. For the intrinsic conductivity of the CuO2 planes a superconducting energy gap of 500 cm-1 (2/kTc8) is evident in the infrared data, while the normal-state conductivity drops much more slowly with than the ordinary Drude form, and can be described in terms of a scattering rate Latin small letter h with stroke*kT+Latin small letter h with stroke at low frequency. The former result (2/kTc8) suggests suppression of Tc; the latter, that YBa2Cu3O7 is not an ordinary Fermi liquid. © 1990 The American Physical Society.