The older preschooler forms long-term psychological mechanisms for activity and behavior that ensure social adaptation. Maladaptive behavior indicates a lack of social skills and requires timely correction. The purpose of this study is to comprehensively diagnose and correct maladaptive behavior in children of senior preschool age. At the ascertaining stage of the experiment, a set of techniques was applied that made it possible to diagnose the factors, manifestations and consequences of maladaptive behavior in older preschoolers. Cluster analysis allowed us to describe the characteristics of children in selective aspects. Statistical analysis revealed that 42.55% of all the older preschool children displayed maladaptive behavior. The diagnosed criteria of maladaptive behavior included assessing factors of maladaptive behavior, identifying manifestation of maladaptive behavior and determining unfavorable group sociometric status. They formed the basis for the development and implementation of remedial programs during the formative stage of the experiment. The programs are aimed at shaping socially adequate behavior in older preschoolers, forming a positive attitude towards enrolling in and attending school, preventing negative emotional states and informing parents about the signs of maladaptive behavior in children. As a result, comprehensive diagnosis and timely correction of maladaptive behavior in older preschoolers ensure their readiness for school.