The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side has motivated many researchers to investigate the combination of both techniques since 1993. This combination, known as multi-carrier spread-spectrum (MC-SS), 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 spread-spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers could be employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals could 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, MCSS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA. The aim of Multi-Carrier Spread-Spectrum & Related Topics is to edit the ensemble of the newest contributions and research results in this new field that will be presented during three days at the Third International Workshop on Multi-Carrier Spread-Spectrum (MC-SS) & Related Topics, held in Oberpfaffenhofen, Germany.