Language plays an important role in social and behavioraldevelopment. Language deficits can lead to behavioral problems bydenying children the ability to express themselves, comprehend others,or effectively cope with a behavioral predisposition and vice versa.Behavior modification is the use of empirically demonstrated behaviorchange techniques to improve behavior, such as altering individual'sbehaviors and reactions to stimuli through positive and negativereinforcement of adaptive behavior and/or the reduction of maladaptivebehavior through its "extinction", punishment or therapy.The present study discusses the nature and complexity ofhuman behavior, the relation between language and behavior, whetherlanguage difficulties lead to behavioral problems, whether behavioralproblems occur as a result of language difficulties, or whether bothlanguage and behavioral problems occur due to a third contributingfactor. The study also goes through behavior modification therapy; itsprinciples, types, advantages, shortcomings, and applications on somedisorders such as Autism Spectrum Disorders (ASD), and AttentionDeficit Hyperactivity Disorder (ADHD).