This study investigates the expansion of the frontostriatal salience network in individuals with depression using precision functional mapping. The authors found that the salience network is nearly twofold larger in the cortex of most individuals with depression, primarily due to network border shifts affecting three distinct modes of encroachment. This expansion is stable over time, unaffected by mood state, and detectable in children before the onset of depression symptoms. Longitudinal analyses revealed that changes in functional connectivity within the frontostriatal circuits track fluctuations in specific symptoms, such as anhedonia and anxiety, and predict future symptom emergence. The findings suggest that salience network expansion may be a trait-like marker of risk for depression and that changes in frontostriatal connectivity can predict the emergence and remission of depressive symptoms over time.This study investigates the expansion of the frontostriatal salience network in individuals with depression using precision functional mapping. The authors found that the salience network is nearly twofold larger in the cortex of most individuals with depression, primarily due to network border shifts affecting three distinct modes of encroachment. This expansion is stable over time, unaffected by mood state, and detectable in children before the onset of depression symptoms. Longitudinal analyses revealed that changes in functional connectivity within the frontostriatal circuits track fluctuations in specific symptoms, such as anhedonia and anxiety, and predict future symptom emergence. The findings suggest that salience network expansion may be a trait-like marker of risk for depression and that changes in frontostriatal connectivity can predict the emergence and remission of depressive symptoms over time.