Scholars have long argued that inmate behaviors stem in part from cultural belief systems that they “import” with them into incarcerative settings. Even so, few empirical assessments have tested this argument directly. Drawing on theoretical accounts of one such set of beliefs—the code of the street—and on importation theory, we hypothesize that individuals who adhere more strongly to the street code will be more likely, once incarcerated, to engage in violent behavior and that this effect will be amplified by such incarceration experiences as disciplinary sanctions and gang involvement, as well as the lack of educational programming, religious programming, and family support. We test these hypotheses using unique data that include measures of the street code belief system and incarceration experiences. The results support the argument that the code of the street belief system affects inmate violence and that the effect is more pronounced among inmates who lack family support, experience disciplinary sanctions, and are gang involved. Implications of these findings are discussed.