There's a flip side to every coin, and ethnic and cultural diversity within the borders of a nation-state is no exception. Canada, like most modern industrialized countries, boasts a wide array of ethnic groups, most the product of migration movements over the past century. And, as with those other countries, that diversity provides a number of advantages, such as a richer environment in which to live -- richer in terms of cultural attributes -- and a populace that assimilates into a Canadian national identity while preserving the unique elements of each individual ethnicity. Most agree that the United States is a better place for its immigrant heritage, with common ideals regarding freedom of expression and of assembly, for instance, overriding distinctions based upon countries of origin. As Canada has evolved over time, it, too, has emerged as more of a "melting pot" of disparate cultures, with its democratic system providing the basis for the development of a multicultural society.
While Canada has prospered as a multicultural society, however, that diversity contains the seeds of its own potential destruction as a unified nation. Canada's modern origins emerged from its colonial experiences, which resulted in the eastern part of the country reflecting its French heritage and the western part reflecting its British heritage, with the latter prevailing politically, often to the consternation of the former. Divided, as it is, between those French and British influences, Canada's unity has at times been threatened. French Canadian resentments over British Canadian political domination provided the basis for the emergence during the 1960s of a terrorist organization, the Quebec Liberation Front, that waged a violent campaign against British Canadian interests for the purpose of forcing secession. While the QLF's efforts ultimately failed, and while its membership was decimated by arrests, the sentiments that fueled that violent secessionist movement remain under the surface. The lesson, here, is that ethnic and cultural diversity may work to a nation's disadvantage. As Canada has become more ethnically and culturally diverse, those sorts of problems will invariably multiply. During the 1990s, the large population of Tamil Canadians with roots in the then-war-torn nation of Sri Lanka created problems for Canadian authorities interested in preventing that far-away conflict from bleeding into their country.
In short, cultural and ethnic diversity has both advantages and disadvantages for Canada.