It has been debated whether teachers should treat students' grammatical errors in second language writing instruction (Truscott, 1996, 1999, 2010; Ferris, 1999, 2004, 2010). Several meta-analyses have investigated correction effects (e.g. Russell & Spada, 2006; Truscott, 2007). Their findings, however, have been conflicting. A recent trend to distinguish specific grammar error types from one another to evaluate correction effects has attracted much attention in written feedback literature (Bitchener & Knoch, 2010ab; Sheen, Wright & Moldawa, 2009). The present meta-analysis, following the recent trend, attempts to assess different types of focused direct correction effects on learners' acquisition of the English article system. Based on Truscott's (2007) inclusion and exclusion criteria, six and five effect sizes are extracted for direct correction type and metalinguistic explanation type separately from seven focused feedback studies. Both direct correction and metalinguistic explanation have large positive effects on learners' ability to accurately use English articles in their writings in terms of long-term learning. This suggests that direct correction may be sufficient for students' acquisition of English articles. Studies to correct other error types should be conducted in the future. (Contains 3 tables and 1 figure.)