Steady state fluorescence energy transfer experiments were carried out to probe the conformation of single-stranded DNA oligomers covalently bound to the surface of polystyrene latex microspheres. These oligonucleotides can adopt various conformations, from an adsorbed conformation on the latex particle surface to a brush conformation. To study this system, a donor of energy transfer (fluorescein) was covalently attached to the free ends of the oligonucleotides, and an acceptor of energy transfer (tetramethylrhodamine) was covalently bound to the latex surface. The extent of resonance energy transfer was found to be more effective at low pH and low ionic strength, reflecting a shorter distance between the free ends of the oligonucleotides and the latex particle surface. In contrast, the oligonucleotides move away from the surface at basic pH or high ionic strength, becoming more accessible for hybridization with complementary DNA strands and exhibiting less energy transfer. The addition of surfactant, or the presence of a large number of grafted oligonucleotides per latex particle, also promotes a brush conformation.