Rowley Jefferson is Greg's best friend. He is childish and immature like his parents. His parents spoil him a lot. He is really a little younger than Greg. He is an 11 to 13 year old boy. Rowley's real birthday is June 29. Rowley sleeps with stuffed toys which is also a way how he is immature and childish. Greg is a lot mature than Rowley. Rowley is potrayed by Robert Capron.