Youth who suffer from psychiatric disorders are at high risk for negative outcomes, including aggression and substance abuse. Although many youth with psychiatric disorders have endured harsh parenting and/or child maltreatment (CM), differential associations between these experiential factors have yet to be fully explored. Sleep problems have also been implicated in psychiatric disorders and are consistently associated with CM. The overlap and unique contributions of CM and sleep problems to the mental health of youth remains unclear; longitudinal studies from late childhood into adolescence, when psychiatric illnesses frequently onset, are rare. The current longitudinal study examined associations of CM, harsh parenting, and sleep problems with symptoms of four psychiatric disorders: Conduct Disorder, Attention Deficit Hyperactivity Disorder, Anxiety, and Depression. Early adolescent youth with no history of substance use (N = 529) were sampled from a working class, medium-sized city in northern Kentucky, and an extensive battery of tests were administered to youth and a parent. CM was more strongly and consistently related to psychiatric disorder symptoms at baseline than was harsh parenting. Reports of harsh parenting were more strongly associated with externalizing symptoms than internalizing symptoms. Sleep problems were also positively associated with psychiatric disorder symptoms at baseline, but did not exacerbate the effects of CM or harsh parenting on symptom counts. Longitudinally, harsh parenting was more predictive of change in psychiatric symptoms two to three years later than was CM. The potential significance of childhood adversity and sleep problems for prevention of later mental health problems are discussed.