There is a gap in the existing literature as to why the New Left in West Germany entered a phase of rapid decline by the end of the 1070s. The overarching aim of this thesis is to offer a politico-theoretical explanation for the historical development of the New Left and why the 'red decade' between 1967 and 1976/77 ended so abruptly. Within this context, the thesis will focus on the Maoist K-Gruppen and particular emphasis will be placed on the Marxistische Gruppe., which defied the general decline of West Germany's New Left and developed into its largest organisation during the 1980s. Furthermore, the Red Cells movement will be analysed from which both currents emerged in the wake of the student movement. In conclusion, this thesis will reveal that the influence of politico-theoretical aspects on the historical development of the New Left has been given too little consideration and that the New Left's fate cannot be adequately explained by external factors, but demands the consideration of the very development of theories and the practical conclusions organisations reached regarding their social, economic and cultural circumstances. This work will be the first to provide an insight into the potential of such a theoretical explanation for an understanding of the specific developments of the post-1968 West German New Left.