The benefits and success of multi-carrier (MC) modulation on one hand, and the flexibility offered by spread spectrum (SS) techniques on the other, have, since 1993, motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: the spreading is performed as direct sequence SS (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers can be employed. The MC modulation and demodulation can easily be done in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. This means that the MC-SS system performs the spreading in the frequency domain, which allows for simple signal detection strategies. Since 1993, MC-SS has been extensively researched and new alternative solutions have been proposed. Meanwhile, deep system analyses and comparisons with DS-CDMA have been performed that show the superiority of MC-CDMA. This book, which consists of seven parts, contains a collection of papers, dealing with all aspects of MC-SS, presented at the Second International Workshop on Multi-Carrier Spread-Spectrum (MC-SS) and Related Topics, held from September 15-17, 1999 in Oberpfaffenhofen, Germany. It will be an invaluable reference for all researchers and practitioners working in the area of wireless communications and networks.