Chapter 2 showed that when the exact question being asked is mirrored in a laboratory experiment and the population being studied is the same as in the field, the outcomes from the experiment can be just as clear and informative. This result suggests that when either the exact question being asked is not mirrored or the population being studied differs, the outcomes from the experiment probably do not parallel those observed in the field. This chapter uses this insight to draw four lessons for experimental design using the games, methods, and results from the previous chapters. Among these lessons are that Major League Soccer players would not be an appropriate pool of subjects to conduct the type of study implemented in Chapter 2, and that a zero-sum situation played among friends does not represent the way subjects interact in the field.