This paper presents a detailed study of the determinants of social status as set out in Críth Gablach (c. AD 700), an Irish law tract on social classification which attempts a systematic analysis of the status of the free and noble classes (excluding the church and the professions) in early medieval Irish society. The nature and determinants of status are considered and the ranks of society set out in detail. To be a noble was to be hereditarily a lord of freemen in clientship – lordship rather than actual income ennobled, though other factors were relevant. For the non-noble freeman, a house, land and material assets are the basis of status. Lordship, however, appears to be economically central to the condition of the non-noble grades. Críth Gablach is one of the few outstanding pieces of social analysis from early medieval Europe.