"The Sea of Monsters" received mostly positive reviews. Reviewers praised the plot, the themes and the author's style of writing. "Publishers Weekly" in their review said the book was better than its prequel, "The Lightning Thief". "School Library Journal" praised the novel's plot and its characters. They said that Percy was an appealing character and said readers would like the "chilling prophecy" which was a part of the plot. "Child" magazine also praised the style of the book. They said it was similar to "The Lightning Thief", and added that the series would get many new readers. "Children's Literature" said the writing was "extraordinary" and added, "...[t]his book, sequel to "The Lightning Thief", is an amazing mixture of mythology and young adult fiction." Matt Berman, of Common Sense Media, praised the book, saying "The Percy Jackson series continues to be pure fun, with the author doing nearly everything right to produce a book that few kids will be able to resist." Norah Piehl of Kidsreads.com also gave a positive review. She praised the book's style and said it was similar to the previous book in the series It sold over 100,000 copies in hardcover by the time paperback copies were released in April 2007.