Snow glide, slip of the entire snowpack over the ground, is not observed unless water reaches the ground interface. In this paper, snow gliding is approached from the point of view that a perfect slip condition is attained at the glide interface whereby a thin continuous water film is envisioned to exist between the snowpack and the ground. Two mechanisms are described by which the snowpack may move forward: (i) creep (defined as slow, viscous deformation) over roughness asperities under the condition that the snowpack conforms to the interface and (ii) rigid body sliding of the snowpack over the interface when it does not conform to the interface. Constitutive equations relating tangential drag on the snowpack to slip velocity are derived for these idealized cases, and the extension to the more realistic case where the processes compete is discussed.