Abstract: A convertible brassiere that converts from the general brassiere configuration to a backless configuration that is not visible when wearing backless apparel. Interchangeability of the present invention relates to certain features of construction to provide an end product of a backless brassiere. In a preferred embodiment, the backless configuration is achieved by manipulating and positioning the shoulder straps and the horizontal back strap of the brassiere. The shoulder straps are detached from the horizontal back strap and attached to the base extremities of the brassiere cups to convert to the backless configuration. Further, there are open vertical slits, within the brassiere cups, into which the extended ends of the unattached horizontal back strap is inserted when converting the brassiere to the backless configuration.