This special issue appears on the occasion of the centenary of the Russian October Revolution and deals with the interrelations of two phenomena that are, historically, closely related with this event: socialism and development. The Soviet Union became the first state socialist model of development in existence, but other socialisms, whether by revolution or peaceful transition, followed. As state socialism spread, it also developed and diverged through the creative adaptation to changing local and global circumstances. Showing how people and ideas circulated through East-South and South-South relations, this issue broadens our understanding of the global historical dimension of development as its highlights the variety and interrelations of socialist experiences and analyses forms of both cooperation and competition between socialisms in the wake of decolonisation and the Cold War.