A unitary disposable garment, such as disposable training pants, having a high degree of stretch in the cross-machine direction and fitting a broad range of wearer sizes. The unitary disposable garment is manufactured from a chassis and has a waist opening, two leg openings and a pair of side seams which join the front portion of the chassis to the rear portion of the chassis. The unitary disposable garment preferably has an absorbent assembly, i.e. an absorbent insert, secured to the inner layer of the chassis. The chassis from which the unitary disposable garment is manufactured, has four elasticized ear flaps; each ear flap is elasticized by securing an elastomeric element thereto and mechanically stretching the ear flap and the elastomeric element such that the ear flap is elastically extensible in the direction of initial stretching. The front portion of the chassis is then joined to the rear portion of the chassis on each side of the disposable garment by a seam.