ABSTRACT Optical tweezers have become a powerful tool to investigate nucleic‐acid processing proteins at the single‐molecule level. Recent advances in this technique have now enabled measurements resolving the smallest units of molecular motion, on the scale of a single base pair of DNA. In parallel, new instrumentation combining optical traps with other functionalities have been developed, incorporating mechanical manipulation along orthogonal directions or fluorescence imaging capabilities. Here, we review these technical advances, their capabilities, and limitations, focusing on benchmark studies of protein‐nucleic acid interactions they have enabled. We highlight recent work that combines several of these advances together and its application to nucleic‐acid processing enzymes. Finally, we discuss future prospects for these exciting developments. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 704–714, 2016.