Harvey Muskrat and feuding sister Mildred have more than a surface resemblance to Frances badgered by little sister Gloria. Their first quarrel (over where Harvey may hammer on his raft) is cooled by a wise father: "Mildred, it's true that Harvey is selfish and inconsiderate, but he is not stupid and no-good"; "Mildred is loudmouthed and bossy, but she is not mean and rotten." Punishment over, the two resume fighting--in the very same words--about who started the trouble, and part, Mildred to go to a party where "little brothers are not invited," Harvey to go to a secret club where "big sisters are not allowed to be members." On the second day of stubborn seclusiveness, Harvey, lonesomely cooking bacon in his underground den, decides to enlarge it and discovers Mildred, lonesomely serving her doll in a den next to his. They trade accusations, then team up to picnic and party together. The illustrations amount to Frances in full color. The Hobans, as usual, know what makes kids kick. Lots of them will find Harvey's Hideout.

-- Kirkus Reviews, April 1st, 1969.