Background: Nursing competency is a standard component of the nursing curriculum in baccalaureate nursing education in Taiwan. However, limited studies have been found on the development of a measurement for assessing Taiwanese baccalaureate-level nursing competency. Objective: The aim of this study was to develop and validate a Nursing Students Competence Instrument (NSCI) for Taiwanese baccalaureate-level nursing students. Design: The items of this newly developed scale were derived from a previous published qualitative study by the authors. Validity and reliability of the instruments were assessed with exploratory factor analysis. In considering external validity and homogenous characteristics, data were collected from two periods of time: February 2011 and 2012. Setting: Four hundreds nursing students enrolled in the 2-year baccalaureate-level at the study university in Taiwan were invited to participate in the study. Participants: Two hundreds and nine nursing students in the 2-year baccalaureate-level program were recruited. Methods: Descriptive statistics and exploratory factor analysis were used to determine validity of the instrument. Cronbach alpha, split-half coefficients and item analysis verified the reliability of instrument. Results: Significant levels of reliability and validity for the newly developed Nursing Student Competency Instrument were found. The competency instrument comprised four dimensions with 27 items for graduates to meet to determine their nursing competency. Four factors were analyzed and categorized as integrating care abilities, leading humanity concerns, advancing career talents, and dealing with tension, and explained 22.29%, 18.59%, 15.99% and 11.23% of total variance, respectively; these four explained 68.09% of the total variance. Conclusions: Results support validation of the new nursing competence assessment scale for Taiwanese nursing students at baccalaureate levels. The authors recommend that the NSCI could be applied in the nursing schools to evaluate the learning outcomes of nursing students' competence.