This work reports the fabrication and characterization of multilayered gold nanoparticle (AuNP) thin films on aminosilane functionalized substrates. The films are fabricated via layer-by-layer (LbL) assembly using as-synthesized, un-modified AuNPs and poly(allylamine hydrochloride) as the building blocks. While most literature reports that AuNP based LbL assemblies are constructed with a single interlayer binding force, this work shows that both coordination and electrostatic interaction are involved in the process of assembly based on X-ray photoelectron spectroscopic results. The stepwise film growth behavior is demonstrated by atomic force spectroscopy and UV-vis spectroscopy. It is found that the particles agglomerate with each other and form large clusters when the number of assembled layers increases. (C) 2007 Elsevier Inc. All rights reserved.