This paper introduces two arbitrage-based tests of target-zone credibility using a new data source, ERM cross-rate options. Using daily option prices from September 1991 to August 1994, we assess the credibility of the pound-mark and mark-lira target zones that collapsed in September 1992, and the ongoing mark-French franc target zone. These tests are based on restrictions that must apply to all option prices within a credible target zone, and are free from specification error and estimation error. We also identify a minimum "intensity of realignment," an expression indicating the probability-weighted average realignment size.