Working memory (WM) is one of the most studied cognitive constructs in psychology, because of its relevance to human performance, including language processing. When measuring verbal WM for sentences, the reading span task is the most widely used WM measure for this purpose. However, comparable sentence-level updating tasks are missing. Hence, we sought to develop a WM updating task, which we termed the selective updating of sentences (SUS) task, which taps the ability to constantly update sentences. In two experiments with Finnish-speaking young adults, we examined the internal consistency and concurrent validity of the SUS task. It exhibited adequate internal consistency and correlated positively with well-established working memory measures. Moreover, the SUS task also showed positive correlations with verbal episodic memory tasks employing sentences and paragraphs. These results indicate that the SUS task is a promising new task for psycholinguistic studies addressing verbal WM updating.