This paper gives an overview of the literature on Malagasy dialect variety and the various Malagasy dialect classifications that have been proposed. It rejects the often held view that the way Malagasy dialects reflect the Proto- Austronesian phoneme sequences *li and *ti is a basic criterion for their genetic division. While the linguistic innovations shown in, respectively, central dialects (Merina, Betsileo, Sihanaka, Tanala) and southwestern dialects (Vezo, Mahafaly, Tandroy) clearly show that these groups form separate historical divisions, the linguistic developments in other (northern, eastern, and western) dialects are more difficult to interpret. The differences between Malagasy dialects are generally rather contained and do not seem to be the result of separate migration waves or the arrival of linguistically different migrant groups. The paper ends with a list of subgrouping criteria that will be useful for future research into the history of Malagasy dialects.