The essentially automatic ordering and assembly of certain molecules into a large structure. Examples of such large molecular structures include micelles, reverse micelles, ribosomes, and Tobacco Mosaic Virus (TMV). The first discovery of a self-assembling active biological structure occurred in 1955, when Heinz Frankel-Conrat and Robley Williams showed that TMV will reassemble into functioning, infectious virus particles (after TMV has been dissociated into its components via immersion in concentrated acetic acid).