It has recently been suggested that speakers vary in the amount of speech planning they do and that the scope of planning is influenced by task and speaker specific constraints. To test this, an experiment is presented examining the effects of linguistic structure and working memory on speech planning, as evidenced in pause duration and F0 peaks. Twenty speakers of German performed two tasks. In the first, speakers' working memory span was evaluated. In the second, an acoustic speech production task, the influence of phrasal length on pause duration and on the utterance initial F0 peak was tested. The hypothesis is that speakers with higher WM span will show evidence of larger scopes of planning, compared to speakers with low WM span, such that they will have longer pause duration and their F0 will start higher. Results show an effect of phrase length and of WM span on F0. The implications of these findings for models of speech planning are discussed