Many methods for the fabrication of nanoparticles have been developed ranging from lithographic techniques to chemical methods. This research group has been exploring a fabrication method termed template synthesis for the preparation of a variety micro- and nanomaterials. This process involves synthesizing a desired material within the pores of a porous membrane. Because the membranes that are used have cylindrical pores of uniform diameter, a nanocylinder of the desired material is obtained in each pore. Depending on the properties of the material and the chemistry of the pore wall, this nanocylinder may be solid (a nanofibril) or hollow (a nanotubule). The intent of this chapter is to provide an overview of the template method. We will start with a brief description of the types of membranes used for template synthesis. Next, the different types of chemistries that have been used to prepare template synthesized nanostructures will be reviewed. Finally, we will discuss fundamental properties and applications of template synthesized metal and semiconductor nanostructures.