The Mennonite house of western Canada offers a special opportunity to examine the effects of migration on traditional building form. The Mennonite house developed as a distinct form in the Vistula River Delta, near the city of Gdansk, during the 16th and 17th centuries. The Vistula Mennonite house was carried to the Russian Ukraine and later to North America with little change in form. After undergoing a gradual evolution in western Canada, the traditional Mennonite form was abandoned, reflecting major changes in the farm economy and the overwhelming influence of the dominant Anglo-Canadian culture. A similar process could be observed among those Mennonites who remained in northern Poland until the second world war. There, an increasing assimilation into the dominant German (Prussian) culture resulted in the adoption of German building traditions. Few examples of the traditional Mennonite house remain in the various regions where it was once commonly found. It is hoped that international cooperation can lead to the preservation and interpretation of this unique Lower Saxon-Slavic building form.