is the stripping of the warm gas in the outer halo of in–falling spiral galaxies, via tidal interactions with the cluster potential. This process removes the reservoir of hydrogen which replenishes the gas in the cold disk of the galaxy, and thus slowly strangles (or starves) the star–formation in the disk leading to a slow death (see Larson et al. 1980; Diaferio et al. 2000; Balogh et al. 2000). Recent N–body simulations of this model by Bekki et al. (2002) demonstrate that it is a viable and can happen at large cluster radii (or low densities).

One possible observational consequence of this strangulation of star–formation is the existence of red, or passive, spiral galaxies, [*i.e.*]{}, galaxies that possess a spiral morphology, but have no observed on–going star–formation. Such galaxies have been found already in studies of high redshift clusters of galaxies (Couch et al. 1998) and have been known for sometime at low redshift as “Anemic Spirals” (see van den Bergh 1991), although their true nature has been debated by many (see Bothun & Sullivan 1980; Guiderdoni 1987 and the review of van Gorkom in these proceedings). Goto et al. (2003) has performed an automated searched for such “Passive” or 