A two‐dimensional model is used to study the comparative roles of advection and turbulent diffusion in controlling tracer transport in the meridional plane in the mesosphere. The Lindzen gravity wave drag and diffusion model is used to parameterize the effects of gravity waves on the zonal mean circulation. Sensitivity tests are conducted to determine the comparative roles of the mean meridional circulation and vertical diffusion by small‐scale turbulence in accounting for tracer transport. We compare a case in which turbulent diffusion by gravity waves is modeled using Lindzen's parameterization for the vertical eddy diffusion coefficient with a case that employs a much reduced diffusivity based on calculations by Schoeberl. Integrations are carried out for a simulated annual cycle in order to test the sensitivity of the tracer distribution to the assumed magnitude of the vertical diffusion coefficient. In both cases, eddy diffusion plays a secondary role compared to tracer advection by the mean meridional circulation for tracers with chemical lifetimes greater than about 10 days. We conclude that global transport in the mesosphere for long‐lived tracers, such as water vapor and carbon monoxide, is dominated by advection, and that for such tracers the eddy diffusion coefficient used in one‐dimensional chemical models of the mesosphere should be regarded as a parameterization of the transport by the meridional circulation, not as a parameterization of mixing by small‐scale diffusion.