Coherent writing skill is an important prerequisite for academic success, especially at the tertiary level. This work studied the effect of four-month teaching intervention of genre pedagogy with Reading to Learn (R2L) approach for developing coherence in argumentative writing. It was implemented on 40 undergraduate Pakistani English Language Learners (ELLs). Pre-test evaluation informed learning gaps especially at theme choice and theme progression strategies in their argumentative writings. These gaps were addressed while planning the R2L teaching cycle of ELLs' experimental group. They were assisted through a process of scaffolding with an aim to enable them to write coherent argumentative essays independently after learning. Then functional analysis of lexical and grammatical features of their independent argumentative writings was conducted. Findings revealed that genre pedagogy had a significant effect on students' organization of argumentative writing. This study suggests genre pedagogy as a useful instructional technique, which can improve teaching and learning writing skills at the tertiary level in Pakistan.