Homologous recombination is the major pathway to repair DNA double-strand breaks in high fidelity. The assembly of recombinases in DNA to form nucleoprotein filaments is the rate-limited step and is tightly regulated. The assembly requires the formation of a stable nucleus followed by the extension of recombinases. There are accessory proteins that modulate the stability of the Dmc1 nucleoprotein filament and regulate recombination events. We used single-molecule tools to directly measure the nucleation, extension, and disassembly of recombinases in DNA in real time to highlight how accessory proteins affect these events at the molecular level. The dynamic nature of recombinases on the filament allows regulatory strategies for efficient recombination progression.