This dissertation describes a theoretical, experimental, and modeling investiga- tion of the plasma irregularities in equatorial spread F (ESF). The primary sci- entific objective is to evaluate the electrodynamic nature of equatorial F region plasma instabilities. In particular, the difference between two-dimensional and three-dimensional electrodynamic effects on the onset and evolution of equato- rial instabilities is investigated. Statistical studies are performed using the Jicamarca Unattended Long Term Investigations of the Ionosphere and Atmosphere (JULIA) radar at Jicamarca. The climatology, persistence, and the correlation with the phase of the moon of equatorial spread F irregularities are evaluated, and different forecasting tools are compared. A three dimensional electrostatic numerical model of the equatorial iono- sphere using a finite volume method transport scheme is desc...