Gerald and Piggie are best friends. Gerald is careful. Piggie is not. Piggie cannot help smiling. Gerald can. Gerald worries so that Piggie does not have to. In Happy Pig Day! Piggie celebrates her favorite day of the year! But will Gerald the Elephant be included in the festivities? Using vocabulary that is perfect for beginning readers (and vetted by an early-learning specialist), Mo Willems has crafted a heartfelt story about celebrating the special occasions in life. Fans of the Geisel Award-winning duo will want to join the party!