Cygnus X-1 is a high-mass X-ray binary with a black hole compact object that typically resides in a hard spectral state, where it is extremely bright in hard X-rays and low energy gamma rays and much fainter in the soft X-rays. Since 2008 August, we have used the Gamma-Ray Burst Monitor (GBM) on Fermi to monitor Cyg X-1 in the 8-1000 keV energy range using the Earth occultation technique. Starting in 2010, Cyg X-1 was observed by GBM to enter a period of increased activity, making several transitions to the soft state, characterized by the typical rise in the soft X-ray flux and decrease in the flux in the hard X-rays and low energy gamma rays, as well as transitions to intermediate states and back to the hard state.
We have generated long-term, broad-band light curves based on daily monitoring of Cyg X-1 over a $sim4$ year period showing the hard to soft state transitions and the transitions back to the hard state, as well as the several broad flares observed during some of the soft states. Spectra generated from the GBM occultation data showed that Cyg X-1 continued to be in an unusually hard state from the beginning of the Fermi mission up to the first soft state transition in 2010 July. Since then, Cyg X-1 has made three additional hard to soft transitions, and spectra from these subsequent states are also shown.