This paper is an empirical investigation of the use of hesitation phenomena, specifically filled pauses (ums and ers), automatisms (sort of, at the end of the day), repetitions and reformulations, in both the mother tongue (L1) and second language (L2) of highly proficient adult bilingual speakers (English and German). Its purpose is to ascertain: i) whether speakers who are highly proficient in L2 produce an approximately similar amount of hesitation phenomena in both languages; and ii) whether the production of such elements (in both languages) is linked to working memory capacity. Results show that: i) despite high proficiency, speakers produced a higher overall rate of hesitation phenomena in their L2, indicating that there was an additional cognitive load imposed by working in L2; and ii) in each language there was an underlying negative relationship between memory capacity and the production of hesitation phenomena, implying that speakers with lower memory ability rely more heavily on such time-buying devices. Furthermore, it was shown that the individual types of hesitation phenomena produced by speakers in their L1 were carried over into their L2, which suggests that a speaker's planning behaviour is mirrored in both languages.