Introducción English teachers should find new ways to make their teaching more effective. Current teaching methodologies include the use of technology to foster students´active participation. In this context, flipped classroom is a student-centered approach that aims to increase students’ self-learning development where technological opportunities enhance the process of learning. Bergmann and Sams (2012) argue that flipped classroom is a student-centered learning method consisting of two parts with interactive learning activities during lessons and individual teaching based activities using technology out of the lesson. Flipped classroom is based on the idea that teaching is inverted and what is done in class (learning), must be done at home and what is done at home (such as homework) must be done in class (Asmara et al., 2019). Mehring (2017) states that flipped classrom requires higher levels of student responsibility. Panopto (n.d.) claim that to flip a classroom teachers need to prepare themselves and the students for using the flipped classroom model. Teachers should create or find curated videos or any other reading material and assign tasks that students should complete to master the the new contents before class. During the class, teachers should solve questions about the topics checked and provide students with activities to solve mainly in a collaborative way. Productive skills are important because they are observable and the proof that learning is happening.. Writing is a skill that requires conveying thoughts, feelings and ideas in a written form using words, phrases, clauses, sentences,and paragraphs (Spratt et al., 2011). Objetivos The main objectives of this study were to determine the effects of using flipped classroom in the development of the writing skils. To assess the level of the writing skill before and after the implementation of the flipped classroom. To determine effectiveness of the use of the flipped classroom to develop the writing skills. Método This investigation was developed using a quantitative approach with an pre-experimental design. To gain insight of the variables an in-depth analysis of previous research works, dissertations, and books was developed to build the theorethical review. To gather information a pre and post test based on the writing section of the Cambridge Advanced English standardized test was applied to a group of 26 university students. To analyze the effects of using flipped classroom to develop the writing skill an intervention proposal was developed. It included lessons in which students worked both in a synchonous and asynchronous way with the implementation of several technological resources such as: Google classroom, Ed-puzzle, Google docs, Google forms, a What´s app and Zoom. To analyze the results a Paired Sample T- test was used Principales resultados The results of students’ scores on the pre-test and post-test CAE writing paper were analyzed. To assess the pieces of writing, a Cambridge rubric with the 4 subscales (Content, Communicative Achievement, Organisation, Language) was adapted. Figure 1 shows that in the pre-test the lowest score was 8 over 20 and the highest grade was 19 over 20. On the other hand, in the post-test the lowest grade was 12 over 20 and the highest grade was 20 over 20. Table 1 shows the average score obtained in both tests. In the pre-test, the average score that students from seventh semester obtained was 13 over 20 that represents 67.4%. Meanwhile in the post-test, they get 17 as the average score that is 87.4%. Therefore, students improved 2 points more as a class, this represents a 20% of improvement in their writing skills. The results show that after using flipped classroom students improved their writing skills. Conclusiones By implementing flipped classroom, students seemed more comfortable writing a text making them more organized and accurate. By watching videos at home, they learnt useful information about how to write an essay and a proposal and reinforced important information in class through discussions and tasks to practice writing. The students´ performance was identified through the pre-test in which the average score was 6,74 over 10. The mean score from the pre-test was 6.740 while the post-test was 8,740. Having the difference of 2 points. The flipped classroom strategies applied had positive effects on students making learning more meaningful for them. After finishing this research, the use of flipped classroom has been demonstrated to have positive effects in students´ writing skill.