Three classes of medieval lead-tin-glazed ceramics (protomajolica, transition enamel pottery and white enamel pottery), from the archaeological site of Castello del Monte in Montella (Avellino, southern Italy), were investigated. Inductively coupled plasma-mass spectrometry (ICP-MS), optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy (OM and SEM-EDS) and X-ray powder diffraction (XRPD) were carried out on ceramic bodies, coatings and decorations in order to outline the technological features and define the nature of glazes and pigments. The aim of this work, in addition to delineating the features of production, is to confirm the archaeological hypothesis that transition enamel pottery produced between the fourteenth and fifteenth centuries, although having much in common with the protomajolica, is in fact a version of white enamel pottery, characterised by morphological and ornamental diversity. Our results show that both ceramic bodies and coatings feature different structural and compositional characteristics, linking the three ceramic classes and making it possible to confirm the archaeological hypothesis that transition enamel pottery can be defined as a ceramic class with transitional features between protomajolica and white enamel pottery.