The Penetration-Aspiration Scale is an 8-point, equal-appearing interval scale designed to describe penetration and aspiration events during swallowing. Scores are determined by the depth of material passage in the airway and whether material is expelled. Intra- and interjudge reliability have been established. The scale is intended for clinical and scientific use to better understand the effects of aspiration on health. Impaired swallowing can result from abnormal changes in swallowing structures or movements. Aspiration, defined as the passage of foreign material into the airway, can have varying clinical significance based on factors such as the person's health, mobility, cognition, and the type of material aspirated. Previous methods of describing aspiration have had reliability and validity issues, but have supported recent advances in understanding aspiration's effects. The 8-point Penetration-Aspiration Scale is introduced as a tool to improve understanding. Penetration is defined as material passing into the larynx but not below the vocal folds, while aspiration is defined as material passing below the vocal folds. The scale was developed based on evaluations of swallowing events in dysphagic subjects. The 9-point scale was reduced to 8 points by combining scores 5 and 7. The final 8-point scale is multidimensional, considering both the depth of material invasion and the swallower's response. The scale is ordinal, with higher scores indicating more severe dysphagia. Aspiration is scored 6, 7, or 8, while penetration is scored 2, 3, 4, or 5. The scale is represented schematically in Figure 1.The Penetration-Aspiration Scale is an 8-point, equal-appearing interval scale designed to describe penetration and aspiration events during swallowing. Scores are determined by the depth of material passage in the airway and whether material is expelled. Intra- and interjudge reliability have been established. The scale is intended for clinical and scientific use to better understand the effects of aspiration on health. Impaired swallowing can result from abnormal changes in swallowing structures or movements. Aspiration, defined as the passage of foreign material into the airway, can have varying clinical significance based on factors such as the person's health, mobility, cognition, and the type of material aspirated. Previous methods of describing aspiration have had reliability and validity issues, but have supported recent advances in understanding aspiration's effects. The 8-point Penetration-Aspiration Scale is introduced as a tool to improve understanding. Penetration is defined as material passing into the larynx but not below the vocal folds, while aspiration is defined as material passing below the vocal folds. The scale was developed based on evaluations of swallowing events in dysphagic subjects. The 9-point scale was reduced to 8 points by combining scores 5 and 7. The final 8-point scale is multidimensional, considering both the depth of material invasion and the swallower's response. The scale is ordinal, with higher scores indicating more severe dysphagia. Aspiration is scored 6, 7, or 8, while penetration is scored 2, 3, 4, or 5. The scale is represented schematically in Figure 1.