Ligation-mediated method of recombining polynucleotides in vitro. Polynucleotides from a library are fragmented and the fragments are hybridized to an assembly template. The hybridized fragments are iteratively re-hybridized and ligated until the ends of the hybridized fragments are adjacent to the ends of other hybridized fragments on the assembly template. A final ligation produces recombined polynucleotides.