Diagnosis in Dermatology is the art of recognition and not the art of cognition. Hence a good understanding of the morphology and distribution of the lesions would guide the Dermatologist in taking a good history to clinch the diagnosis. This chapter gives a systematic approach to the diagnosis of dermatological disorders with emphasis on history taking, clinical examination and laboratory tests. The section on clinical examination describes in detail the morphology and distribution of lesions with clinical photographs and pictorial representations respectively. The various clinical signs and phenomena in dermatology have been described in detail with their pathogenesis and the conditions where they occur. Also, the various diagnostic laboratory tests performed are discussed concisely.