By creating a location that is essentially free from radioactive background, sensitive measurements can be performed to test fundamental laws of physics with neutrinos from the Sun, Dark Matter particles left over from the Big Bang and rare forms of radioactivity. The Sudbury Neutrino Observatory (SNO) is a neutrino detector containing 1,000 tonnes of heavy water and situated 2,000 meters underground in INCO's Creighton Mine near Sudbury, Ontario. SNO has observed neutrinos from the core of Sun and has found clear evidence for neutrino flavor change. This requires modification of the Standard Model for elementary particles and confirms solar model calculations with great accuracy. The underground facility is now being expanded to create a long-term international facility for underground science (SNOLAB), where measurements of Dark Matter, Double Beta Decay and Solar Neutrinos will be performed with the lowest radioactive background available anywhere. The results for SNO and the future scientific program for SNO and SNOLAB will be described.