Western Austronesian languages, like Tagalog, have unique, complex voice systems that require the correct combinations of verbal and nominal markers, raising many questions about their learnability. In this article, we review the experimental and observational studies on both the L1 and L2 acquisition of Tagalog. The reviewed studies reveal error patterns that reflect the complex nature of the Tagalog voice system. The main goal of the article is to present a full picture of commission errors in young Filipino children’s expression of causation and agency in Tagalog by describing patterns of nominal marking and voice marking in L1 Tagalog and L2 Tagalog. It also aims to provide an overview of existing research, as well as characterize research on nominal and verbal acquisition, specifically in terms of research problems, data sources, and methodology. Additionally, we discuss the research gaps in at least fifty years’ worth of studies in the area from the 1960’s to the present, as well as ideas for future research to advance the state of the art.