What happens to language when humans age? Is there a decline in the language abilities in old age? Do performance patterns in the elderly change when compared to those of younger individuals? What variables can explain these changes? In order to answer these and other questions, the authors present the most relevant theories developed to explain age-related cognitive effects in language comprehension and production processes, for instance slowing, inhibitory deficit, transmission deficit, working memory decline. Furthermore the most notable findings of gerontology-based psycholinguistic research are reviewed, covering all language processing levels. It also takes into account the language comprehension and production phenomena regarding word, sentence and discourse levels. The problem analysis is completed with contributions from neuropsychology as critical issues are discussed related to search methods used in the area and the role played by social and cultural factors.