People tend to idealize eco-labeled products, but can eco-labeling have consequences for performance To address this question, 48 university students were asked to undertake a color discrimination task adjacent to a desktop lamp that was either labeled “environmentally friendly” or “conventional” (although they were identical). The light of the lamp labeled “environmentally friendly” was rated as more comfortable. Notably, task performance was also better when the lamp was labeled “environmentally friendly”. Individual differences in environmental concern, but not pro-environmental consumer behavior and social desirability indexes, were related to the magnitude of the eco-label effect on performance. Whilst some previous studies have shown similar placebo-like effects of eco-labels on subjective ratings, this is the first study to show an eco-label effect for artifacts in the built environment on performance, and the first study to relate this effect to environmental concern. Psychological mechanisms that may underpin the eco-label effects are discussed.