The trajectory of an electrically charged droplet falling in air and electrostatically deflected is analyzed for the influence of droplet size, air frictional drag, and electrical charge. An analytical solution for the trajectory was obtained (assuming a linear velocity component) and programmed into a computer to generate graphs of the variation in trajectory. The experimental work verified that the droplet deflection is proportional to charge and the loss of velocity in the direction of deflection is predicted from the equations obtained here. These studies were used in designing a cell sorting device which places biological cells in defined locations on a microscope slide.