Although optimization of recombinant protein production is an important part of expression, it is difficult to provide “cookbook” techniques. We will instead outline general approaches to optimization with specific methods described where appropriate. Optimal titers are reached by designing an environment where growth, viability, and specific productivity (protein/cell/time) are balanced so as to give maximum titers (protein/volume of medium). The strategy used will depend on the cell line and the characteristics of the protein being produced. Other considerations are the amount of protein needed, how much time is available for developing the process, and whether production of the protein will need to be repeated. Additionally, purification is much more efficient if the starting material contains a significant proportion (10–80%) of the protein of interest.