This chapter focuses on summarizing aberrant brain connectivity of individuals with stimulant addiction as compared with a control group, as well as brain–behavior correlations. Four major networks/brain systems implicated in stimulant addiction are discussed: the reward system, the salience network, the executive control network and learning networks. Resting-state functional connectivity therefore captures a default brain state independent of external input/challenges, providing insight into the intrinsic ‘functional architecture’ of the brain that underlies functioning during task demands. Resting-state functional and structural imaging are novel tools that can deepen our understanding of the structural and functional architecture of the brain at baseline, independent of task performance. The dysregulation of the reward system in chronic drug abusers is associated with compromised inhibitory self-control pronounced especially during stages of craving and drug consumption. In conclusion, results support a fundamentally altered baseline state of brain functioning in individuals with stimulant addiction.