The objectives of this dissertation are: to identify the behavior of pupils with ADHD, distinguishing between desirable and undesirable behaviors; to describe the teaching interventions based on using behavior modification techniques in response to the desirable and undesirable behaviors of pupils with ADHD; and to analyze the effect of the behavior of pupils with ADHD after the teaching intervention, determining whether the behavior remains the same or is changed after the intervention. This is a study of multiple cases in which six PE teachers and six pupils in the 4th, 5th and 6th grades diagnosed with ADHD participated throughout a school year. The researcher adopted the role of non-participant observer. He used field notes to identify the behavior of pupils with ADHD, to describe the teaching interventions and to analyze their effects on pupils\u2019 behavior. He then interviewed the PE teachers in order to complement the information from the observations. The quantitative data were analyzed via descriptive and inferential analysis. The qualitative data were analyzed via the analysis of the content of the narrative records. The most noteworthy results were that desirable behaviors were observed 19% of the time and undesirable behaviors 81%. Likewise, 16% of teaching interventions based on theories to increase or maintain conduct were used (praise, attention, physical contact, rewards and privileges), while 84% of teaching interventions observed were based on techniques to lower or eliminate the behavior (differential reinforcement of low rates, RTB, punishment, response cost, time out, directive instructions, interrogative instructions, informative instructions and elimination). The most important conclusions are: a) the teachers have to create situations in which desirable behaviors occur more frequently: avoid queues when doing an exercise, including explanations during the activity itself; avoid lengthy meetings to explain a new situation; control the length of explanations; ask pupils to participate in the explanation or be part of the demonstration led by the teacher during class; physical proximity between the teacher and pupils when giving explanations, among others; b) more frequently use techniques to increase or maintain behavior; and c) use reinforcement techniques or positive techniques (RTB) more than punishment, elimination or instructions, given that the study shows that they are also effective.<\/p>\n\n