Formal political theory has raised serious doubts about the existence of strategic voting, and this in turn has challenged the prevailing wisdom in comparative politics about phenomena like squeezing and the effect of the wasted vote. This paper attempts to set out the conditions for strategic voting and to test for it using data from the 1970 British General election. The results from both an aggregate and a survey analysis indicate that individuals are more likely to vote for their second preference when they perceive that their first choice has little chance of winning. This effect is particularly strong when the next best party is at a margin of under five percent.