We report here direct evidence for Neanderthal mobility through the measurement of strontium isotope ratios in tooth enamel using laser-ablation, which allows us to use much smaller samples than traditional methods. There has been a long-standing debate over the extent of Neanderthal mobility, with some arguing for Neanderthals having a very limited geographic range and others for more substantial, and even seasonal, lifetime movements. We sampled across the enamel of a Neanderthal third molar from the site of Lakonis, Greece, dating to ca. 40,000 years ago. The tooth was found in a coastal limestone cave, yet the strontium isotope values indicate the enamel was formed while the individual resided in a region with bedrock consisting of older (more radiogenic) volcanic bedrock. Therefore, this individual must have lived in a different (more radiogenic) location during this period of third molar crown formation (likely to be between the ages of 7 and 9 years) than where the tooth was found. This strontium isotope evidence therefore indicates that this Neanderthal moved over a relatively wide (i.e. at least 20 km) geographical range in their lifetime.