This chapter considers the experimental approaches for examining the effects of vesicular-arbuscular mycorrhizae (VAM) on plant growth, the effects of VAM on nutrient uptake specifically, and the effects of VAM on plant growth other than those related to increased nutrient uptake. There are several procedures which should be employed in experiments which are designed to test the effect of VAM on plant growth. The difficulties in choosing a control treatment, which is identical to the inoculated treatment in all respects but does not include the VAM fungus, cannot be ignored. There are at least two advantages in comparing the response curves of mycorrhizal and nonmycorrhizal plants to applied nutrients. A major difficulty with using complete response curves for mycorrhizal and nonmycorrhizal plants is that the size of experiments may become excessively large and unmanageable. Sequential harvests can be of great benefit in experiments designed to test the effect of VAM on plant growth.