There is an increasing interest in improving youth digital citizenship through education. However, the term ‘digital citizenship’ currently covers a broad range of goals. To improve education, the current article argues for a narrower focus on (1) respectful behavior online and (2) online civic engagement. Using this definition, a digital citizenship scale was developed and assessed with a sample of 979 youth, aged 11–17 years, and confirmatory factor analyses (CFAs) supported measurement of both constructs: online respect (7 items, Cronbach’s α = .92) and online civic engagement (4 items, Cronbach’s α = .70). Online respect scores decreased with youth age, and scores on both subscales were higher among girls than boys. Both online respect and civic engagement were negatively related to online harassment perpetration and positively related to helpful bystander behaviors, after controlling for other variables. Implications of the study findings for developing and evaluating digital citizenship educational programs are discussed.