The Dutch overestimate their English speaking skills. Their pronunciation is not always convincing and certain pronunciation mistakes are easily recognised as being typical for Dutch speakers of English. Although intelligibility cannot exist without adequate pronunciation, teaching English pronunciation at Dutch secondary schools is often absent from the EFL teaching curriculum. Focussing on the most prominent pronunciation difficulties, often caused by the mother tongue (L1), will benefit the non-native speaker’s pronunciation and intelligibility. In order to provide teachers with a time-efficient approach to teach English pronunciation, preliminary research is needed to establish the most prominent error types in the English pronunciation of secondary school pupils and bachelor students in the Netherlands. Research shows that fifty percent of the subject group makes seven types of pronunciation mistakes in more than fifty percent of the cases that such mistakes could be made. The conclusion discusses a general approach for addressing the kind of pronunciation problems we identified.