This study uses articulography, the measurement of the position of tongue and lips during speech, as a tool to quantitatively assess the differences between pronunciations of native and non-native (Dutch) speakers of English. In our study, we focus on two pairs of English sound contrasts: /s/-/ʃ/ and /t/-/θ/. Our analysis focuses on the anterior-posterior position of the tongue tip during the pronunciation of minimal pairs containing the contrasting sounds. Our results indicate that the contrast between /s/ and /ʃ/ made by the Dutch L2 speakers is slightly reduced compared to the contrast produced by the English L1 speakers. For the contrast /t/-/θ/, our findings show that while native English speakers clearly produce this contrast, Dutch speakers do not. Our results line up with earlier studies on the basis of acoustic data, and also illustrate that articulography is a suitable method of investigating pronunciation differences between first and second language speakers.