Tooth discoloration and developmental defects of enamel and dentin are frequently observed in the pediatric dental clinic. Proper diagnosis may improve the clinicians dental care in many aspects: caries and risk assessment, esthetic restorations and their prognosis, adhesion of restorations and orthodontic appliances, individual and community perspectives of prevention (dental trauma, fluorosis, genetic counseling, financial considerations), behavioral management, and medico-legal issues. This article presents a differential diagnosis of tooth discoloration. External and internal causes for staining and pigmentation are presented in a form resembling the differential diagnosis of developmental defects of enamel. The correlation between these two entities is emphasized and elaborated to schematically review the etiology for developmental and acquired tooth discolorations.