The Attention Control Scale (ACS) appears to be a reliable, valid self-report measure of attentional control. It is a widely used scale due to its clinical and heuristic utility. Impairments in attentional control have been associated with a range of psychiatric disorders. The original ACS (ACS-20) is a 20-item, 4-point Likert scale measuring two factors, attentional focusing (9 items) and attentional shifting (11 items). The shorter version has 12 items (ACS-12). The initial psychometric evaluation reported ACS-20 had three factors, namely, focusing, shifting, and flexible thought control. Later independent evaluations have confirmed ACS has two factors, namely, focusing and shifting. Both versions (ACS-20 and ACS-12) are strongly correlated. The ACS-20 has been translated to French, Polish, German, Persian, and Slovakian with satisfactory internal consistency and discriminant validity. Independent studies have found supporting evidence for the internal consistency and discriminant validity of both scales across a range of samples. However, additional research using performance-based tasks or physiological tasks is needed to verify the scales’ convergent validity, predictive validity, test-retest reliability, and split-half reliability. Notable limitations with ACS include the bias associated with the self-reported nature of the scale, convenience sampling, convergent validity, factor structure, and limited independent evaluations. A range of study designs from cross-sectional studies, randomized controlled trials to structural equation modeling have investigated how mindfulness improves attentional control.