This study explores the use of mindfulness school-based intervention program in an elementary school. Mindfulness training is an accepted and effective didactic approach to improve the executive functions (EFs) of elementary school students. This study aimed to evaluate the effects of the Mind Yeti program on the executive functions of elementary school students. A diverse sample of third, fourth, and fifth grade elementary school students (n = 177) participated in their natural classroom setting, with six sessions per week for six weeks. Students self-reported their EFs on the Executive Function Student Questionnaire (EFSQ) pre-and posttest. Paired-sample t-tests indicated that students significantly improved on the three of the six EFs examined. Additionally, students in fifth grade responded better to Mind Yeti than students in third grade. Results were consistent with the hypothesis, suggesting that Mind Yeti is an appropriate and effective intervention for improving the EFs of students. 545 changes in the brain, which is thought to improve EFs as it "fosters enhanced resilience and more optimal brain function" [10].With regard to the use of instruments for assessing mindfulness with young children there are remarkable studies worth to mention like the Child Observation of Mindfulness Measure (C-OMM) [11] proving to be relevant during teacher-directed activities only or the Individualized Classroom Assessment Scoring System (In-Class) to assess children's behaviors as they pertain to desirable social behaviors requiring trained observers to note, interpret, and code select children's behaviors related to their experiences with teachers, peers and tasks [12].In addition, there are multiple MBI programs and curricula marketed to schools for use with elementary school students and they have "differences in the underlying content, methods, dosage, and effectiveness" [13]. For example, Semple et al. [14] conducted an open trial, pre-posttest design study where seven and eight year old elementary students with high levels of anxiety received six weekly, forty-five minutes MBI training using an adapted version of the adult Mindfulness-Based Cognitive Therapy (MBCT) and Mindfulness-Based Stress Reduction (MBSR) intervention programs. The intervention was implemented by a researcher in a small group setting outside of the students' regular classroom. The finding indicated that the mindfulness training improved students' anxiety and inattention. However, the sample size was extremely small (five students) and students received the intervention outside of their classroom setting. A recent study using a pretest and posttest pilot quasi-random assignment on 45 students between seven and nine years old was conducted by Nadler et al. [15]. The researchers implemented a 10-min mindfulness practice (mindful stretches with a guided breath-based meditation) or a quiet play activity led by outside instructors and found that students' self-reported calmness improved. Again, the sample was small, and the intervention was conduc...