After deconstructing the palimpsest of level O, we present a cross-disciplinary study on a short occupation of the Abric Romaní rock shelter conducted by means of an analysis of the record of archaeo-level Oa, a Middle Palaeolithic assemblage dated to ca. 54 Ka BP by U/Th series. In this study, we present the steps we took to puzzle out the palimpsest of level O and identify a short-term occupation in archaeo-level Oa. Occupational patterns are identified based on anthropogenic accumulations, archaeological accumulations consisting of stone artefacts (1496 remains), faunal remains (486 remains) and hearths (n = 11). The relationship between them has been established through refit analysis. The small occupation surfaces (55 m2 of the 209 m2 palaeo-floor of archaeo-level Oa) and the results obtained (fragmented knapping activities, isolated accumulations and differential transport of lithic remains) suggest short-term occupation settlements in archaeo-level Oa.