Keratinocytes and fibroblasts isolated from dysplastic oral lesions were combined to provide a renewable source of epithelia. A dysplasia-scoring index was devised to compare the architectural and cytological features and used together with robust immunophenotyping to show that the engineered epithelia showed most of the characteristics of the clinical lesions. The strains of dysplastic oral keratinocytes with an extended or immortal lifespan provided a reproducible resource of epithelia showing mild (DOK), moderate (POE9n) or severe (D20) dysplasia when maintained under defined conditions. The dysplasia score was influenced by growth conditions, with KGF polarizing proliferation to the basal layer and reducing the severity of dysplasia. When compared to the normal counterparts, dysplasia-associated fibroblasts expressed MMP9, secreted more HGF, increased the dysplasia score for epithelia generated with mortal dysplastic keratinocytes and induced morphological changes in normal keratinocytes, highlighting the role of the microenvironment in determining the phenotype of dysplastic epithelia.