Development of reading skills has been shown to be tightly linked to phonological processing skills and to some extent to speech perception abilities. Although speech perception is also known to play a role in reading development, it is not clear which processes underlie this connection. Using event-related potentials (ERPs) we investigated the speech processing mechanisms for common and uncommon sound contrasts (/ba/-/da/-/ga/ and /ata/-/at: a/) with respect to the native language of school-age children in Finland and the US. In addition, a comprehensive behavioral test battery of reading and phonological processing was administered. ERPs revealed that the children could discriminate between the speech sound contrasts (place of articulation and phoneme length) regardless of their native language. No differences emerged between the Finnish and US children in their change detection responses. The brain responses to the phoneme length contrast, however, correlated robustly with reading scores in the US children, with larger responses being linked to poorer reading skills. Finnish children also showed correlations between the reading and phonological measures and ERP responses, but the pattern of results was not as clear as for the US children. The results indicate that speech perception is linked to reading skills and this link is more robust for uncommon speech sound contrasts.