In both phonetics and sociolinguistics, it has been widely observed that speech style is situation dependent. Both fields have studied this topic autonomously. When the results of sociolinguistic studies and phonetic studies on stylistic vowel variation are combined, a paradox (referred to as ‘the Vowel Space Paradox) arises. On the one hand, phonetic studies have found that more informal speech yields a smaller vowel space in comparison with formal speech, i.e. vowels in the vowel space are reduced in more informal speech, as compared to their realization in formal speech. On the other hand, sociolinguistic studies have repeatedly shown that some vowels show more sociolinguistically conditioned variation in less formal speech. Thus, individual vowels can cover a larger area in this smaller vowel space, as compared to these vowels in formal speech. At the same time, it has been shown that in more informal speech contrasts between vowels remain largely intact, despite the smaller overall vowel space and the larger individual vowel spaces. The current dissertation explains and solves this paradox by investigating the sociogeographic variation in read and spontaneous speech of speakers of Standard Dutch. In addition to explaining the paradox, this study gives experimentally based recommendations on methodological issues as formant measurements,optimal temporal representations and normalization of vowels. Therefore, this dissertation is of interest to anyone who studies vowel variation. Finally, it offers a description of sociogeographic variation in the pronunciation of Standard Dutch vowels.