Given the considerable policy and practical importance of digital skills and literacies for young people’s life chances, especially as regards inequalities and digital inclusion, and the increasing reliance on digital technologies for learning, employment and civic life, a systematic evidence review was conducted to answer this question. The review was informed by the International Telecommunication Union’s (ITU) definition of digital skills: "the ability to use ICTs in ways that help individuals to achieve beneficial, high-quality outcomes in everyday life for themselves and others" and to "reduce potential harm associated with more negative aspects of digital engagement" (2018, p.23). A preliminary rapid evidence mapping found that relatively little research was published in the early years of mass internet use (2000–09). Hence the systematic evidence review encompassed all research published between 2010 and 2020, thus representing the large majority of available studies. The search protocol, registered on PROSPERO, included studies of moderate to high quality (judged using the Weight of Evidence approach) that used quantitative methods, were published in the English language, and related directly to the digital skills of 12- to 17-year-olds. The results of 110 studies were analysed to identify what is known about youth digital skills, and to examine the evidence for the antecedents (or factors influencing the acquisition) of digital skills, and the consequences of having digital skills. They were also scrutinised for research gaps and to generate questions and hypotheses for future investigation. In addition, they were examined for the many ways in which digital skills have been conceptualised and measured in the research literature.