This study focused on the characteristics of an action-research study concerning an English language reading and writing intervention program in a primary state school, located in northeast Portugal (low-Socio Economic Status setting), where four groups of children (n = 92) participated in the academic year 2019–2020, after the National strategy for foreign languages was launched. The longitudinal study carried out in the action-research methodology, where the teacher, syllabus designer and researcher was the main author, was set out with two main aims. The first was to tackle and to overcome the lack of teacher training for teaching English to young learners in Portuguese primary schools. The second was to prompt intervention, through the design and implementation of a suitable pedagogic approach for teaching English to young learners, in line with Content for Language and Integrated Learning (CLIL) principles, namely English Across the Curriculum, thus fostering the interrelationships between English language reading and writing skills. The findings of the action-research reading intervention program demonstrate that it is possible to overcome such barriers as pupils’ negative attitudes and counteract the damaging effects of poverty in foreign language literacy development by exposing them to children’s picturebooks/storybooks, thus fostering the overall literacy development. The key concepts explored in these books, being associated with primary key curriculum themes are an effective way to establish clear positive connections among English language reading and writing relationships. In addition, the current study also sheds light on how primary English language school teachers can design suitable pedagogic approaches to foster overall literacy development, thus advancing innovative teacher training opportunities.