The process of gastric carcinogenesis involves the loss of parietal cells (oxyntic atrophy) and subsequent replacement of the normal gastric lineages with metaplastic lineages. In humans, two metaplastic lineages develop as sequelae of chronic Helicobacter pylori infection: intestinal metaplasia and Spasmolytic Polypeptide-expressing Metaplasia (SPEM). Mouse models of both chronic Helicobacter infection and acute pharmacological oxyntic atrophy have led to the recognition that SPEM arises from transdifferentiation of mature chief cells. The presence of inflammation promotes the expansion of SPEM in mice. Furthermore, studies in Mongolian gerbils as well as increasing evidence from human studies indicates that SPEM likely represents a precursor for development of intestinal metaplasia. These findings indicate that loss of parietal cells, augmented by chronic inflammation, leads to a cascade of metaplastic events. Identification of specific biomarkers for SPEM and intestinal metaplasia hold promise for providing both early detection of pre-neoplasia as well as information on prognostic outcome following curative resection.