In this talk I will present a theoretical perspective on low-energy searches for physics beyond the Standard Model. I will first provide an overview illustrating the breadth of questions addressed by low-energy searches. I will then discuss selected examples from two classes of probes: precision tests of processes allowed by the Standard Model (such beta decays) and searches for rare / forbidden processes (such as neutrino-less double beta decay). Throughout, I will highlight the high impact of these probes as well as the theoretical challenges and progress associated with their interpretation.