This study explores whether Ben Sira’s textual use of the Psalms may shed light on the Qumran Psalms Scroll debate. It is proposed that Ben Sira’s quotations of Psalms 104, 147, and 148 in Sir 43:11–19 could point us to which Psalter Ben Sira may have used, since these three psalms are found in close proximity to each other in 11QPsa and 4QPsd. Doing so will allow us to better gauge Ben Sira’s relationship to 11QPsa. Issues such as the 364-day calendar, Sir 51:13–30, and pluriformity are considered. This article finds that the debate is still open as to which Psalter Ben Sira used, either proposal equally remaining possible at this stage, needing more analysis from the rest of Ben Sira’s text. Remarkably the examples and analysis do not yield anything yet to positively disqualify the 11QPsa-Psalter from being used by Ben Sira.