Abstract:  In skin, cohesion between the dermis and the epidermis is ensured by the dermal–epidermal junction which is also required for control of epidermal growth and differentiation. Here we showed that addition of vitamin C optimized the formation of the dermal–epidermal junction in an in vitro human reconstructed skin model leading to a structure closer to that of normal human skin. Compared with controls, vitamin C treatment led to a better organization of basal keratinocytes, an increase in fibroblast number and a faster formation of the dermal–epidermal junction. Vitamin C also accelerated deposition of several basement membrane proteins, like type IV and VII collagens, nidogen, laminin 10/11, procollagens I and III, tenascin C and fibrillin‐1 at the dermal–epidermal junction. The mechanism of action of vitamin C was investigated by quantitative polymerase chain reaction in fibroblasts and keratinocytes respectively. Vitamin C effects passed in part through an increase in col I alpha1, col III alpha1 and fibrillin‐1 mRNA levels. Effects on the other markers appeared to happen at the translational and/or post‐translational level, as illustrated for tenascin C, col IV alpha2 and col VII alpha1 mRNA levels which were reduced by vitamin C in both cell types.