This article is a scale development study aimed at developing valid and reliable scales to understand English language teachers' knowledge about and attitudes towards plurilingualism and interculturalism. It is a descriptive survey model of quantitative research. During the scale development phase, literature review was conducted to develop the item pool. Then, 81 items were adapted from The Framework of Reference for Pluralistic Approaches to Languages and Cultures (FREPA). The draft scale was applied to 349 pre-service English teachers who are third and fourth year university students from five state universities in Turkey. As a result of these analyses, a knowledge scale consisting of 20 items with three factors and an attitude scale with 14 items including three factors were obtained. The reliability of the Plurilingual and Intercultural Knowledge Scale (PIKS) is 0.829, and the reliability of the Plurilingual and Intercultural Attitude Scale (PIAS) is 0.874. Based on the performed analyses, the 5 points Likert-type PIKS and PIAS were developed.