A micrometre-sized laser has been demonstrated in silicon, the most ubiquitous material of the electronics industry. The device operates at microwatt power levels and could open routes to compact photonic integrated circuits. See Letter p.470 Silicon is the workhorse of the microelectronics industry, but its performance as a 'photonic' material is not exceptional. Nevertheless, much progress has been made in imparting useful optical properties to silicon, culminating in the realization of an all-silicon laser. Yasushi Takahashi and colleagues now present a new architectural twist on the silicon laser, showing how the incorporation of a photonic-crystal nanocavity into such a structure can drastically reduce both the size and the threshold power (the power at which it starts to behave as a laser) of the resulting device — both features that are essential for large-scale integration with other photonic and electronic circuitry.