In this chapter, we discuss the roles that nuclear magnetic resonance (NMR), and an exploitation of the NMR phenomenon that identies spatial information, termed magnetic resonance imaging (MRI), play in the monitoring of tissue-engineered devices. To do this instructively, some preliminary eort will be spent on describing the phenomenon of NMR, and how imaging with NMR came to be achieved. is description of NMR will be done in a “classical” rather than a quantum mechanical fashion, so that although the details may not be completely accurate, the reader can still gain a deeper understanding of the advantages and disadvantages of the NMR technique with minimal diculty, and with no advanced mathematical treatment. Next, we describe some methods that have been developed to enhance the NMR signal and allow users to obtain important information that may otherwise be obscured. e chapter then discusses some approaches to monitor in vitro systems, as in vitro data can be critical to the basic understanding and development of functional tissue-engineered constructs. e in vivo application of MRI to observe implanted constructs is then reviewed, with a mention of several organ/ construct systems of potential interest. e given list of these organ systems is far from complete, and serves merely to demonstrate the power and potential scope of the NMR method. Finally, this chapter concludes with a detailed example of an application, that of monitoring an implantable bioarticial pancreas, as a means to illustrate the rationale for using NMR/MRI, and how this, or a similar approach, can be tailored for the desired application. It is hopeful that through reading the pages of this chapter, the reader will obtain a greater insight into the power of NMR/MRI, as well as gain an understanding of its limitations, so that the techniques described here can be considered for future data gathering. e ultimate goal of this chapter is to provide sucient information on NMR so that this technique can be considered as a potential tool in the hands of the researcher, physician, and scientist interested in the eld of tissue engineering.