It is hoped that this chapter has shed some light on the issues associated with defining the spatial and temporal resolution limits and the sensitivity in fMRI. New pulse sequences and new imaging hardware are being developed constantly and, combined with a better understanding of the physiological changes that occur with brain activation, the ability to obtain high resolution fMRI studies in short exam times will continue to improve. There are many trade-offs to be made in deciding on the imaging sequence and parameters to use, and it is hoped that this brief overview will shed some light on the issues involved. Clearly, because many trade-offs must be made, an understanding of these issues will help the investigator to tailor some of these parameters to the specific brain region or study design of interest.