In the last few years, great interest has been generated in the selective growth of single crystal silicon in seed windows of an SiO2mask in order to fabricate novel device structures for VLSI/ULSI device technology. This increased interest in selective epitaxial growth (SEG) and its derivitives, simultaneous single/poly deposition (SSPD) and epitaxial lateral overgrowth (ELO) have led to several key processing breakthroughs that are currently changing the future direction and usage of silicon epitaxy. This paper will describe: 1) the key SEG processing breakthroughs that have occurred over the last 25 years, 2) some of the current limitations still observed with SEG processing and, 3) some of the novel device structures that are possible through the use of SEG techniques.