Recently, researchers have devoted greater attention to understanding how disagreement between mothers and their children regarding parent-child relationship quality and functioning impacts youth adjustment. While some view discrepancies as indices of developmentally appropriate individuation, discrepancies regarding family functioning also have been found to predict problematic youth functioning. This study examined the effects of mother-child discrepancies for mother-child relationship qualities and youth self-disclosure on youth- and mother-reported youth internalizing and externalizing adjustment. 232 fifth, eighth, and 11th grade youth (55 % female) and their mothers completed measures of mother-child relationship quality, youth self-disclosure, and youth internalizing and externalizing adjustment. For internalizing adjustment, few effects of discrepancy on adjustment were evident. Instead, informant-specific perceptions of mother-child relationship functioning were most relevant for informant-specific reports of youth adjustment. For youth externalizing adjustment, the magnitude of mother-child discrepancies for negative relationship quality and for youth self-disclosure predicted lower levels of problematic externalizing behavior from both the children's and the mothers' perspectives, which could indicate a lack of parent-child communication. Future research is needed to fully understand how discrepancies in negative or maladaptive aspects of mother-child relationships are formed (e.g., low disclosure), are understood by the members of the dyad, and contribute to the onset, maintenance, and treatment of problematic behavioral outcomes.