The Red Layer Microbial Observatory (RLMO) aims to survey and compare alkaline mat communities throughoutYellowstone National Park, all of which contain distinct layers of red, filamentous bacteria we have identified as atypical red Chloroflexi using 16S rRNA, pigment spectroscopy, and microscopic methods. The RLMO Database Project is a Web-accessible OracleTM database that integrates physical, chemical, and molecular data from RLMO sites. This application, in its second year of development, was written using PL/SQL, HTML, and Javascript. Each research site in this study is assigned a unique identifier that is linked to the following tables: Geochemical Data (pH, 15 common salts and metals); DNA Sequence Data (16S clone name, GenBank-linked accession number, BLAST-inferred identity); Macroscopic and Microscopic Image Data; and Student Collection Team Information. Using the administrative URL, all data can be entered and edited through restricted Web access. Using the public URL, users can view and query data. Site Query results can be formatted to display any combination of geochemical parameters across one or more years and/or sites. Sequence Query results can be formatted to display inferred identity and GenBank-linked accession numbers across one or more sites. The RLMO Database, in its current form, is designed to accommodate physical, chemical, and molecular information as part of a five-year study to address whether observed variation in geothermal ground water chemistry affects the population distribution of genetically distinct strains of Chloroflexi in red layer communities.