New Delhi, June 14 -- Switzerland heads to the polls on Sunday for a referendum that could fundamentally reshape the country's relationship with immigration, the European Union, and the multinational companies that have made it one of the most prosperous economies on earth. At issue is a proposal to cap the country's population and tighten immigration rules to enforce that limit, a move that supporters say is necessary to manage rapid growth and that critics warn could unravel decades of economic success.

The referendum asks Swiss voters whether to impose a legal ceiling on the country's population and mandate that the government introduce immigration restrictions to keep it there until 2050.

The backdrop is a decade of significant demo...