The aim of this study was to investigate the relationship between compensatory shortening and coarticulation in German tense and lax vowels and to determine whether this relationship was influenced by prosodic accentuation. While previous studies focussed on temporal vowel reduction due to compensatory shortening, and often found conflicting results, our study extends previous results by including a formant analysis of spatial reduction in two types of compensatory shortening. Polysyllabic shortening was tested in monosyllabic versus disyllabic words, while incremental coda shortening was tested in words with final singleton versus final cluster. Speakers produced minimal pairs differing in vowel tensity in accented and deaccented contexts for both shortening conditions. Vowel duration was influenced primarily by vowel tensity as well as by accentual lengthening for tense but not lax vowels. While vowel duration was not affected by compensatory shortening, formant analyses revealed an effect of coda cluster for tense vowels as well as clear effects of accentuation and vowel tensity. There was no effect of polysyllabic shortening on formants. Further to previous studies on compensatory shortening, these results reveal that compensatory shortening is not limited to temporal reduction, but can have an impact on vowel quality as well.