In this chapter we consider the nature and origin of dawn-dusk asymmetries in the ionospheric convection pattern. We focus on asymmetries that are introduced via solar wind-magnetosphere-ionosphere coupling when the interplanetary magnetic field (IMF) has a strong dawn-dusk component. In particular, we address the interplay between flows that are “directly driven” by dayside coupling processes and those driven over a variety of longer timescales by internal magnetospheric dynamics. This produces variability in the ionospheric convection and leads to an inherent time dependence in the development of dawn-dusk asymmetries. Our discussion focuses on the interpretation of observations made by the Super Dual Auroral Radar Network (SuperDARN), which has provided measurements of the two-dimensional ionospheric convection pattern at 1 or 2 min resolution for the last two decades. We summarize the current state of understanding in this area and discuss unanswered questions.