Peter Billingsley plays the child Ralphie who follow through the various times of his young life up until Christmas as he tries every way he can think of to get a Red Ryder BB gun with a compass in its stock and a thing that tells time. The film also is narrated by an adult Ralphie who recounts these exploits in a dry humorous fashion who is played by the writer of the film's source material, Jean Shepherd. This is not about Shepherd's performance though this is about Billingsley's portrayal of Ralphie. Child acting is not always where one finds the greatest performances as it can often be the most self-aware type of work, or just obviously inexperienced type of acting. Billingsley is even in a role that could have gone either of these ways. Firstly since the adult Ralphie talks much more than the boy, and a lesser actor may have just been kind of a non-entity. Secondly though Ralphie technically is a bit of wiseguy type kid in many respects, which could lead to that all too knowing sort of obvious type of acting.
Well Peter Billingsley is a particularly natural child actor in the film, and most importantly just makes Ralphie believable as a kid first and foremost. Ralphie may have some particularly snarky thoughts about certain things, as told by his future self, but Billingsley does not use this as an excuse to be overly precocious in his characterization. Billingsley strikes up a certain balance between showing the side of Ralphie that alludes to the adult version, but also the side of him that shows that Ralphie simply is just kid. Billingsley does this though by never letting either being the deciding factor for the character, and really just pretty flawlessly maneuvers these sides in his performance making everything he does seem distinctly Ralphie. He does not shift from one side to another really, as that would not make any sense. Instead he makes sense of the mind of a boy like Ralphie by always believably changing from one side of boy's life to another.
The most emotional moments are usually pretty simple scenes such as either Ralphie is getting punished for swearing or fighting, or perhaps a particularly happy moment like at the end of the film. Billingsley doesn't treat this moments with a great deal of humor, but is effective by just being to the point and showing how a fairly young boy would react. When punished for his "crimes" Billingsley is very good by making the sadness in Ralphie very much on the surface yet still intense in its own way. He very correctly cries at being punished not the crying of some great depression, but the sadness of the moment which can be rather extreme for a kid. Billingsley is equally good in showing the happiness at the end of the film as Ralphie finally gets what he wants. The enthusiasm and love in his eyes in the scene is unabashed in nature, and again shows a boy who's dream at the moment has just been fulfilled. Bilingsley even is convincing in the scene where he beats the bully going from fury to crying in a second. It may seem odd, but Billingsley's is absolutely convincing in showing such a sudden shift of emotion to seem completely natural for a kid.
Of course this is not a drama but a comedy at heart. The majority of his performance is more of Ralphie humorous reactions to various opportunities and setbacks involving his relatively simple life. In this regard much of his performance is reactive, but that's all Billingsley needs to be quite humorous in the role. Billingsley, once again, importantly always makes these funnier moments seem the antics of a kid with far too much of an imagination rather than just a movie kid type character. Now the most important thing though is that Billingsley is very funny in these reactions, and has some of the most memorable moments in the film. There is of course when Ralphie overplays his hand, naming his Christmas gift too early, followed by a simple "ooh" which Billingsley delivers quite hilariously. Then of course there's the great moment of comedic fear after accidentally uttering an expletive in front of his Old Man, and one must never forget his perfection reaction (pictured above) when he hears from Santa Clause himself that he'll shoot his eye out if he gets his desired present.
Many of Billingsley's best moments are actually quite silent in nature, yet still consistently entertaining. I particularly enjoy his expression, as if Ralphie is almost the referee, when his two friends are testing their debate on whether or not your tongue will get stuck on a frozen pole. Another great moment shortly afterward his face of pure, yet so fake, innocence when Ralphie shakes his head to indicate knowing nothing of what happened to his friend who decided to see if his tongue would be stuck. I have to say, like Christopher Walken in The Dead Zone, Billingsley never seems to waste a reaction. This is a performance that's easy to take for granted since Billingsley just is Ralphie for the duration of the film. Also it should be mentioned that Jean Shepherd's narration also provides to a certain degree the strength of Ralphie as whole, but this should not take anything from Billingsley's performance as he always seems particularly in line with Shepherd's work. The narration and Billingsley's portrayal of Ralphie come together to make one very memorable character.