This longitudinal study examined the influence of child-specific and environmental factors on the development of English receptive vocabulary and grammar by two groups of Danish children: Early Starters (ES) and Late Starters (LS). Age of onset, gender, language aptitude and SES significantly predicted both outcome measures. English competence beliefs (ECB) were positively related to L2 proficiency but only for children with low foreign language classroom anxiety (FLCA), suggesting a dynamic relationship between ECB and FLCA. Extramural audiovisual viewing and reading played a differential role for ES vs. LS whereas extramural English speaking significantly interacted with gender. Finally, child-specific factors explained more of the variance in English proficiency than environmental factors. This finding, which contradicts results obtained in instructed settings (e.g., Sun, Steinkrauss, Tendeiro & de Bot, 2016) but parallels those in naturalistic settings (e.g., Paradis, 2011), supports the special status of English in countries with a high degree of informal contact with English.