Located immediately north of Hong Kong, Shenzhen is China's most successful special economic zone (SEZ). Commonly known as the “social laboratory” of reform and opening, Shenzhen was the foremost frontier for the People's Republic of China's adoption of market principles and entrance into the world economy in the late 1970s. This article looks at prototypes of the SEZ in Bao'an County, the precursor to Shenzhen during the Mao era (1949–76). Between 1949 and 1978, Bao'an was a liminal space where state endeavors to establish a socialist economy were challenged by capitalist influences from the adjacent British Crown colony of Hong Kong. To create an enclave of exception to socialism, Communist cadres in Bao'an promoted individualized, duty-free cross-border trade and informal foreign investment schemes as early as 1961. Although beholden to the inward-looking planned economy and stymied by radical leftist campaigns, these local improvisations formed the foundation for the SEZ—the hallmark of Deng Xiaoping's economic statecraft.