Ultrathin films of quaterthiophene (4T) were deposited on a Ag(111) surface by vacuum sublimation and characterized with respect to their geometric and electronic properties using several surface-sensitive techniques. For the monolayer (1 ML), a long-range ordered superstructure is found by electron diffraction (LEED). This is commensurate to the Ag(111) surface due to covalent bonding of the "flat-lying" 4T molecule via its pi-system. The bonding properties can be deduced from photoelectron spectroscopy results (UPS, XPS). For multilayers (3-20 ML) a gradual decrease of the orientational order is observed by infrared spectroscopy and X-ray absorption.