Many studies have addressed the effect of neighborhood density (phonological similarity among words) on word learning in quiet listening conditions. We explored how noise influences the effect of neighborhood density on children's word learning. One-hundred-and-two preschoolers learned nonwords varied in neighborhood density in one of four listening conditions: quiet, +15 dB signal-to-noise ratio (SNR), +6 dB SNR, and 0 dB SNR. Results showed that a high-density advantage for children under quiet listening condition was significantly reduced as noise increased. This finding implies an adverse impact of noise on long-term outcomes of word learning.