Labor unions play a key role in the defense of workers’ rights and in the construction of more egalitarian societies. Despite this, few empirical investigations have analyzed how attitudes toward labor unions are shaped by subjective manifestations of inequality. Bringing together the sociological and social-psychological research on inequality, in this article we do so by studying how attitudes towards unions are shaped by class identification and by ideal inequality, understood as the level of inequality that people consider ideal or fair. Using data from the 2020 Latinobarómetro survey for 18 Latin American countries, we find that pro-union attitudes are significantly higher among those who identify with the lower-middle class but not among those who identify with the lower class. We also find a negative relationship between ideal inequality, measured by a pseudo-Gini index of ideal inequality, and pro-union attitudes: those who want less economic inequality have more positive attitudes towards unions. Finally, we find that the effect of class identification and ideal inequality is moderated by individual political orientations. At the end of this article, we explain these findings and show how they contribute to the recent research on subjective inequality and attitudes toward labor unions.