This study aimed to develop and validate the Attitudes towards Socioscientific Issues Scale (ATSIS) for undergraduate students. In the first step, data were collected from 160 undergraduate students from the departments of science education and elementary education to provide validity of the scale. In light of the results of an exploratory factor analysis, three dimensions emerged: interest and usefulness of socioscientific issues (SSI); liking of SSI; and anxiety towards SSI. In the second step, data were collected from 216 undergraduate students from the departments of science education, elementary education and social sciences to confirm the factorial structure of the 30-item ATSIS. A confirmatory factor analysis supported the three-dimensional structure of ATSIS. Another important characteristic of an instrument is reliability of the instrument, so Cronbach alpha coefficients for each dimension were computed. For the dimensions of ATSIS, the Cronbach alpha coefficients ranged from 0.70 to 0.90. This study has provided a new scale to the field that is both a reliable and valid instrument. The results also pointed out that the ATSIS distinguished between major and non-major students, in a Turkish setting, with better attitudes towards SSI scores for majors. The author of the present study recommends that the field continues examining attitudes of undergraduate students towards SSI to verify the results of the present study and to produce new evidence about their attitudes. (Contains 2 tables and 1 figure.)