Pesticides are applied in agricultural systems for the purpose of protecting plants from injury by weeds, insects, disease, etc., which today still destroy almost 33% of all food crops. This chapter deals principally with the characterization of spray drift as particulate rather than vapor drift, and the current and possible future strategies of mitigating that type of spray drift. Atomization of liquids for the purpose of applying a mist onto a target results in loss of a portion of the spray cloud in two ways: spray drift, consisting of airborne movement of liquid particles immediately after hydraulic or rotary atomization, and vapor drift which is associated with volatilization. Displacement of pesticides out of the intended target area is not only wasteful, but represents a loss in efficacy and leads to increased costs to the user and the environment. Pesticide drift is affected by several major factors, including chemical/physical properties of the solution, the equipment, weather, and operator care and expertise.