We recently developed a family of self-assembly driven self-replicators (Figure ) where the mechanism of replication offers unique opportunities for enhancing fidelity. These systems are made from peptidefunctionalized dithiol building block(s), which, upon oxidation, yield a mixture of differently sized disulfide macrocycles (rings) that continuously exchange building blocks. Self-assembly of a specific ring size into stacks stabilizes these rings, which are replenished by the exchanging mixture. After an often slow nucleation of the first stacks (fibers), these can grow exponentially through an elongation/fragmentation mechanism until all the material in the system resides in assembled rings of one specific size. Replication arises as the assembly process drives the production of the very rings that assemble. Mixing structurally similar building blocks carrying different peptide tails results in replicating macrocycles of mixed building block composition; i.e. different mutant replicators . High-speed atomic force microscopy studies revealed that small macrocycles (mostly trimers to pentamers) aggregate on the surface of the fibers to form precursor reservoirs from which the replicators (in this particular study, hexamers) grow .