Prior research suggests that real-time phonological competition processes are stabilized in early childhood (Fernald et al., 2006). However, recent work suggests that development of these processes continues throughout adolescence (Huang & Snedeker, 2011; Rigler et al., 2015). This study aimed to investigate whether these developmental changes are based solely within the lexical system or are due to domain general changes. This study also aimed to investigate the development of real-time lexical-semantic activation. We captured semantic activation phonological competition and non-linguistic domain general processing skills using two Visual World Paradigm experiments in 43 7-9-year-olds, 42 10-13-year-olds, and 30 16-17-year-olds. Older children were quicker to fixate the target word and exhibited earlier onset and offset of fixations to both semantic and phonological competitors. Visual/cognitive skills explained significant, but not all, variance in the development of these effects. Developmental changes in semantic activation were largely attributable to changes in phonological processing. These results suggest that the concurrent development of linguistic processes and broader visual/cognitive skills lead to developmental changes in real-time phonological competition, while semantic activation is stable across these ages.