This research study analyzes the effect the implementation of language-driven CLIL has on senior learners from Manuel J. Calle High School in Cuenca, Ecuador in relation to the development of written production in terms of Syntax, Content, Communicative Achievement, Organization, and Language compared to a non-language-driven CLIL classroom. There were 40 participants in the experimental group, and 38 participants in the control group. Learners from the experimental group received a condensed 35-hour intervention using CLIL. This study features an exploratory, mixed-method, and quasi-experimental research design. To collect qualitative data, an open-ended questionnaire was administered to explore the subjects learners preferred to study in a language-driven CLIL classroom. To collect quantitative data, a Pre and Post-Test based on the writing section of Cambridge Objective Primary English Test was administered. The data was analyzed through the Independent T-Test and Paired-T-Test to determine if there was a statistically significant difference present between the language-driven CLIL classroom and the non-language-driven CLIL classroom. The data was calculated through the Statistical Package for Social Sciences (SPSS). A survey was administered to collect data on learners' perceptions about CLIL and then analyzed statistically. Results indicated that learners preferred to study History, Biology, and Spanish Language and Literature. Results also demonstrated that the experimental group also demonstrated improvement in all the examined parameters when compared to the control group. However, when results from both groups are compared, there is only a statistical improvement in Organization and Syntax.