This study investigated the relationship between the perceived externalizing behaviors of children with attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD) and the maladaptive childrearing beliefs of their parents. The study used archival survey data provided by Intervention Services, Inc., a community mental health center. Data from 338 families with a child diagnosed with ADHD or ODD were analyzed. The study used the Conners' Parent Behavior Rating Scale short version to measure the level of conduct problems, impulsivity, and hyperactivity of the children as perceived by the parents. The Adult-Adolescent Parenting Inventory was used to measure the degree of parental belief in the value of physical punishment and lack of empathy towards childrens needs. Both surveys were completed by the parent. Pearson product-moment correlational analyses were undertaken for the total sample and separately for each of four subsamples: 1) males, 2)females, 3)those with ADHD, and 4) those with ODD. The results provided only moderate support for a few of the hypothesized associations between child externalizing behaviors and parent childrearing beliefs. Significant but very modest correlations were found in the total sample, male sample, and ODD sample. The strongest correlation in each sample was between conduct problems and physical punishment. The most interesting finding of the research was the difference in results between the subsamples. For the participants in this study, males and those with a diagnosis of ODD showed a greater correlation between childrearing beliefs of parents and perceived externalizing behaviors than females and those with a diagnosis of ADHD. Future research could focus on the differences in patterns of correlations found between the subsamples.