The mobility of nuclear proteins can be studied by photobleaching techniques. The three main advantages of photobleaching are fast experimental turn around, good spatial and temporal resolution, and the ability to measure kinetics inside of living cells. The main disadvantage of these techniques is the requirement for fluorescently tagged proteins that have rigorously tested to ensure it has the same properties and function as its native counterpart. Three major methods of photobleaching microscopy are described: fluorescence recovery after photobleaching (FRAP), fluorescence loss in photobleaching (FLIP), and inverse fluorescence recovery after photobleaching (iFRAP). Each of these techniques has characteristics permitting the determination of distinct parameters of protein behavior in vivo.