By definition, an “unsignalized” intersection is any at-grade intersection that is not controlled by a traffic signal. The term covers a wide variety of situations, including a) uncontrolled intersections, b) two-way STOP-controlled intersections (TWSC), c) two-way YIELD-controlled intersections, c) all-way STOP-controlled intersections (AWSC), and roundabouts. This chapter details the development of procedures for analysis of TWSC intersections. Chapter 5 will cover AWSC intersections, and Chap. 6 will cover roundabouts.