Informal Digital Learning of English (IDLE) refers to the informal, self-directed English learning using different digital devices (e.g., smartphones, laptops) and resources (e.g., apps, social media) independent of formal contexts. This study examined what IDLE activities Filipino senior high school students are engaged in and investigated whether the time spent on these activities had any correlation with their (a) vocabulary performance and (b) writing performance. It also looked into how IDLE activities affect the students’ vocabulary knowledge and writing skills. This research used quantitative methods including a survey and vocabulary and writing tests among 99 SHS students from Bacolod City, and qualitative methods, namely interviews among selected participants from the sample and their family members. This study demonstrates that the participants engage in a variety of IDLE activities, with the presence of multitasking and parental influence. However, the time they spend on these had no significant correlation with their vocabulary and writing performance. Even with a lack of correlation among the variables, the interview participants cited the different ways how IDLE activities had contributed to their vocabulary knowledge, which may be attributed to their engagement in form- and meaning-focused language learning. Moreover, the results indicate the possibility that the participants’ writing errors were caused by the informal English, slang, and errors in English that they were exposed to online. However, the interview participants still identified the positive influence of IDLE on their writing, such as providing models of good writing. Educators and parents may consider integrating IDLE in their children’s learning of English.
