Abstract: Disclosed is an adapter apparatus useful in conjunction with recording systems employing tape cassettes. The apparatus includes a first and second element for operatively engaging the tape drive element of a tape recorder/playback apparatus, a compartment sized to receive a smaller tape cassette, a magnetic head, and an element connecting the magnetic head of the adapter apparatus to the magnetic head of the tape recorder/playback apparatus. The adapter is configured such that when a smaller cassette is positioned within the compartment the entire apparatus can be substantially flush-mounted in a tape recorder/playback apparatus, that is, the overall profile of the adapter remains unchanged whether or not a smaller cassette is positioned in it.