English as a second language learning has been growing during the last years on a global level and the demands on both students and teachers have increased set by curriculum goals. Educators of today need to cater for development of knowledge and language for students with mixed abilities and assist them in developing metacognitive skills. The formative features of portfolio writing aid the self-assessment process and is revised against the background of young second language learners, as well as their needs when being assessed and their writing development. These are the major themes that compose the framework for the reviewed educational journals articles in this research synthesis. The findings show that portfolio assessment does make an influential difference on English as a second language learners writing development. But the implementation of this method is not always commonly used due to exam oriented educational systems or due to its time-consuming aspect.