The objectives of this chapter are to provide a conceptual framework for how and where the diverse effects of current, both direct and indirect, can be important determinants of benthic algal ecology. The direct effects of persistent currents include the positive effect of turbulent mixing on nutrient transport to benthic algal cells and the negative effect of drag on algal attachment to substrata. There are many indirect effects of current, which I group in abiotic and biotic categories. These range from affecting substratum stability and size to affecting herbivore distribution. Finally, a habitat-by-habitat synthesis will be presented.