[9] In the May/June 2019 issue of Bookmarks, the book received an average rating of 4 out of 5 with the critical summary saying, "All in all, Say Nothing is a "riveting account" (Minnesota Star Tribune) sure to interest amateur historians".

[10][11] Jennifer Szalai of The New York Times wrote, "Keefe's narrative is an architectural feat, expertly constructed out of complex and contentious material, arranged and balanced just so.

"[12] Maureen Corrigan of NPR enthusiastically wrote, "Keefe is a storyteller who captures the complexities of a historical moment by digging deep into the lives of people on all sides of the conflict.

"[13] Corrigan concludes, "At the end of his panoramic book, which gathers together history, politics and biography, Keefe tightens the focus back to the mystery of McConville's abduction and murder.

And, as in the most ingenious crime stories, Keefe unveils a revelation — lying, so to speak, in plain sight — that only further complicates the moral dimensions of his tale.

"[13] Devlin Barrett of The Washington Post described how Say Nothing is "a cautionary tale, [that] speaks volumes — about the zealotry of youth, the long-term consequences of violence and the politics of forgetting.

"[15] Stephen Phillips of the Los Angeles Times praised the book saying, "Say Nothing powerfully documents a society benumbed by trauma attempting to reckon with the abyss that engulfed it.