Web 2.0 technologies offer different resources to learn English in a virtual environment. This study aims to analyze differences concerning self -efficacy beliefs perceived in both linguistic skills and the attitude towards the use of Web 2.0 tools when learning English online with respect to the gender variable. A non -experimental, ex post facto study was conducted following a descriptive -inferential and cross-sectional nature. The sample corresponded to 861 undergraduate students in a public university in Colombia. Findings demonstrated that, under the Flipped Classroom in Synchronous Settings Model (FCISSM) for English Language Learning, men have higher self -efficacy levels than women. Moreover, men use Web 2.0 resources to a larger extent to develop their linguistic skills. Gender differences are linked to intrinsic, extrinsic, and instrumental motivation to the way in which women have assumed the FCISSM and are also connected to a possible sense of 'selfcomplacency' regarding how men assessed their self -efficacy in a foreign language learning (L2). In this sample size, gender is a differential aspect in language learning through the FCISSM, regarding self -efficacy beliefs and the use of Web 2.0. Some pedagogical implications were provided in accordance with the results of the study.