This comparative study examines patterns of inequality in participation in two different types of adult learning and education (ALE) -- job-related formal ALE (JFALE) and job-related non-formal ALE (JNFALE) -- as related to social origins at the micro-level and three categories of social inequality at the macro-level at the macro level (economic, education, and skill inequality). Using data from the Programme for the International Assessment of Adult Competencies (PIAAC), two methods are used to analyse 19 selected OECD countries: multivariate binary logistic regressions to explore the extent to which individuals' social origins are associated with ALE participation and two-stage multilevel analysis to examine the relationship between social origins' advantages in ALE participation and social inequality. Statistically significant advantages in ALE participation of social origins were observed in some countries. Additionally, statistically significant positive relationships between social inequality and social origins' advantages in JNFALE participation are found, which implies that increases in social inequality strengthen advantages associated with social origins.