The formation of nuclei in a crystallization experiment requires the interaction of protein molecules until a critical size of aggregate is created. In many crystallization screens sufficiently high levels of saturation are never reached to allow this critical nucleation event to occur. There are at least two possibilities to change this situation. The first is to increase the concentration of the protein and precipitating agent during the experiment to levels where spontaneous nucleation will occur. The second is to influence the nucleation event so that crystals can form at lower concentrations. The use of a modified microbatch method has made the first strategy possible and the use of heterogeneous seeding can be used to influence the second.