What type of items, keyed positively or negatively, makes social-emotional skill or personality scales more valid? The present study examines the different criterion validities of true- and false-keyed items, before and after correction for acquiescence. The sample included 12,987 children and adolescents from 425 schools of the State of São Paulo Brazil (ages 11-18 attending grades 6-12). They answered a computerized 162-item questionnaire measuring 18 facets grouped into five broad domains of social-emotional skills, i.e.: Open-mindedness (O), Conscientious Self-Management (C), Engaging with others (E), Amity (A), and Negative-Emotion Regulation (N). All facet scales were fully balanced (3 true-keyed and 3 false-keyed items per facet). Criterion validity coefficients of scales composed of only true-keyed items versus only false-keyed items were compared. The criterion measure was a standardized achievement test of language and math ability. We found that coefficients were almost as twice as big for false-keyed items' scales than for true-keyed items' scales. After correcting for acquiescence coefficients became more similar. Acquiescence suppresses the criterion validity of unbalanced scales composed of true-keyed items. We conclude that balanced scales with pairs of true and false keyed items make a better scale in terms of internal structural and predictive validity.