Psychosis is increasingly being understood as a neurodevelopmental ‘dysconnection’syndrome, in which neural connectivity—at both microscopic and macroscopic levels of brain organization—becomes disrupted during late adolescence and early adulthood. Tools to quantify normative brain development and identify individuals at risk are urgently needed to tailor appropriate strategies for prevention and intervention, and could substantially improve clinical outcomes. Resting-state functional connectivity magnetic resonance imaging (rsfc-MRI) provides a rich, functional description of the brain's macroscopic connectivity structure. Over the past several years, rsfc-MRI has evolved to be a powerful tool for studying both normal brain development and abnormalities associated with psychosis. Several recent advances highlight intriguing and potentially significant parallels between these two lines of research. For instance, rsfc-MRI work suggests that psychosis is accompanied by loss of segregation between large-scale brain association networks, a pattern that is normal in early life but typically matures into more segregated systems by young adulthood. Coupled with data sharing across large-scale neuroimaging studies, longitudinal assessments using rsfc-MRI in patients and those at risk will be essential for improving our biological understanding of psychosis and will help inform diagnosis, prognosis, and clinical decision-making.