Nomenclatural changes in Monardella Bentham (Lamiaceae) are introduced to more accurately circumscribe the specific and subspecific entities in the genus in California. Examination of herbarium specimens and digital images and analysis of biogeographical data from additional fieldwork has revealed morphological continuities and discontinuities. Four new species are described: M. boydii A. C. Sanders & Elvin, M. eremicola A. C. Sanders & Elvin, M. mojavensis Elvin & A. C. Sanders, and M. sinuata Elvin & A. C. Sanders. Five new subspecies are described: M. australis Abrams subsp. jokerstii Elvin & A. C. Sanders, M. hypoleuca A. Gray subsp. intermedia A. C. Sanders & Elvin, M. linoides A. Gray subsp. sierrae Elvin & A. C. Sanders, M. sinuata subsp. nigrescens Elvin & A. C. Sanders, and M. undulata Bentham subsp. arguelloensis Elvin & A. C. Sanders. Eight new combinations and/or rank changes are proposed: M. australis subsp. cinerea (Abrams) A. C. Sanders & Elvin, M. breweri A. Gray subsp. glandulifera (I. M. Johnston) Elvin, M. breweri subsp. lanceolata (A. Gray) A. C. Sanders & Elvin, M. breweri subsp. microcephala (A. Gray) Elvin & A. C. Sanders, M. linoides subsp. anemonoides (Greene) Elvin & A. C. Sanders, M. linoides subsp. erecta (Abrams) Elvin & A. C. Sanders, M. undulata subsp. crispa (Elmer) Elvin & A. C. Sanders, and M. venosa (Torrey) A. C. Sanders & Elvin. The description of one taxon is emended: M. undulata subsp. undulata. Lectotypes are designated for M. lanceolata A. Gray and M. sanguinea Greene. We address each of these changes within informal species groupings or alliances.