This chapter looks at recent psycholinguistic and neurolinguistic research that attempted to uncover a lost or suppressed childhood language both in adult and young adoptees as well as in those who were exposed to the language in childhood or learned a foreign language and later claimed to have forgotten it. It focuses on those studies where the search for memory traces of a lost language operates on the assumption that a language, once learned but later forgotten, leaves imprints in the person's brain that later facilitate relearning or identification of that language. The age factor in language acquisition, both first and second, often is related to the so-called critical age hypothesis. The age regression technique is used in hypnosis in order to bring mental images to the mind of an individual and ask them to describe those images, aiming at the individual's speech production in the suppressed language.