The Drossel-Schwabl forest fire model self-organizes to a critical state without parameter tuning. Trees grow at rate p, lightning strikes at rate f≪p. Fires cascade through connected clusters, pruning large ones. Fire size distribution follows a power law P(s)~s^(-τ) with τ≈1.19, a hallmark of SOC. The system perpetually hovers near the percolation transition.