This chapter explores diagnostic techniques and early intervention of caries. To aid in the reduction of dental caries, the disease must be viewed as an infectious disease. The American Academy of Pediatric Dentistry (2007a) developed a caries‐risk assessment tool referred to as the CAT, which can be very helpful in identifying children that may be at a higher risk for the development of caries. The various diagnostic techniques discussed in the chapter are visual examination, transillumination, laser fluorescence, quantitative light fluorescence and radiographs. Early diagnosis of enamel demineralization allows for early intervention to remineralize enamel and the evaluation of the reason for demineralization. The chapter also discusses remineralization of demineralized enamel, restoring cavitated lesions, and cosmetic zirconia crowns. Fluorides have been the principal means of remineralizing demineralized enamel. The zirconia crowns provide excellent esthetics and have shown minimal wear to opposing teeth compared to porcelain.