This paper presents the initial validation of a bilingual (English/Spanish) scale designed to assess intensity of perceived self-efficacy for breast self-examination (BSE) among low-income Mexican American women. The validation and reliability analysis included the use of Cronbach's alpha, factor analysis, and correlations of the measure with knowledge of correct BSE procedure, current level of breast self-examination, and English language proficiency. Cronbach's alpha coefficient demonstrated the reliability (internal consistency) of the scale. Results of the factor analysis supported the construct validity of the perceived self-efficacy measure, and statistically significant correlations with knowledge of correct breast self-examination, frequency of breast self-examination, and English language proficiency substantiate the concurrent validity of the measure. Further testing of the scale is proposed to strengthen the validity of the concept of self-efficacy and its measure. © 1990, SAGE PUBLICATIONS, INC. All rights reserved.