Purpose: This study investigated the role of processing complexity of verbal working memory tasks in predicting spoken sentence comprehension in typically developing children. Of interest was whether simple and more complex working memory tasks have similar or different power in predicting sentence comprehension. Method: Sixty-five children (6- to 12-year-olds) completed a verbal working memory (listening) span task that varied in syntactic processing difficulty (simple sentences representing a "simple working memory task," complex sentences representing a "complex working memory task") and a standardized sentence comprehension test. Results: Word recall on the simple and complex working memory tasks correlated with each other. Both memory tasks also correlated with children's sentence comprehension. Regression analyses showed that the simple working memory task remained a significant predictor of comprehension even after accounting for variance associated with age and performance on the complex working memory task. Conclusions: Results were interpreted to suggest that relative to more complex verbal working memory tasks, simple tasks are more robust predictors of children's sentence comprehension because they represent a basic yet robust index of working memory that sufficiently captures controlled attentional focus.