A new noncovalent and nonorganic method has been utilized in dispersing single-walled carbon nanotubes (SWNTs) in water, up to single tube level. SWNTs, otherwise flocculated in aqueous solutions, were stabilized through the addition of highly charged nanoparticles. The dispersed SWNTs could be self-assembled into macroscopic materials in solutions by the application of external stimuli. By anchoring the solution SWNTs onto pyrene-modified Si/SiO2 surfaces, discrete, individual nanotubes have been observed by atomic force microscopy (AFM). This new type of SWNT aqueous dispersions might open up new avenues in the fields of nanostructured materials, biological sensing, and nanotube electronics.