The present application relates to methods and compositions for triggering RNAi. Triggered RNAi is highly versatile because the silencing targets are independent of the detection targets. In some embodiments, methods of silencing or modulating the expression of a target gene are provided. The methods generally comprise providing an initiator to a cell comprising a detection target and a silencing target gene, wherein the detection target is different from the silencing target gene, wherein binding of the detection target to the initiator initiates formation of an inactivator double-stranded RNA (inactivator dsRNA). The inactivator dsRNA can silence or modulate the expression of the silencing target gene.