Objectives The aim of this study was to develop a brief schema questionnaire for adults (BSQ-A) and investigate its validity and reliability. Methods A 36-item questionnaire was developed or selected by six psychiatrists. The questionnaire was administered to 209 subjects in Seoul and Gyeonggi area. The construct validity was investigated by performing principal component analysis, and the reliability was assessed in terms of the internal consistency using Cronbach’s alpha. Results The principal component analysis revealed 18 factors underlying 18 early maladaptive schemas (EMSs). These 18 factors accounted for 87.488% of the common variance. The Cronbach’s alpha was high, indicating that the reliability of the questionnaire was satisfactory. Every schema showed a positive correlation with most psychological measures. Conclusion The results indicate that the BSQ-A is a reliable and valid scale for assessing EMSs. Although there are many limitations, the present study is expected to form the basis of future research.