This document describes the design methodology for an All-Terrain Vehicle (ATV). It discusses selecting AISI 1018 carbon steel as the material for the roll cage due to its strength, weight, and weldability properties. Circular cross-sections are chosen for the roll cage members to maximize strength and torsional rigidity. The design process involves selecting cross-sections, defining frame parameters, designing the roll cage and its components, and specifying the suspension, steering, and braking systems. Finite element analysis will be performed to validate the design.