Adults who haven't forgotten the fears and traumas of middle school will no doubt get a few hearty chuckles from director Thor Freudenthal's adaptation of Jeff Kinney's popular "Novel in Cartoons," but make no mistake, this one's primarily for the kids. With gags hinging on moldy playground cheese, hairy freckles, booger torment, older bullies, and bratty girls who beat up boys, Diary of a Wimpy Kid relies heavily on juvenile humor to keep its preteen crowd giggling, yet deeper themes about what it takes to be a good friend -- even when it means flirting with social suicide -- will likely resonate with viewers of all ages. Greg Heffley (Zachary Gordon) is about to be thrust into middle school, and despite a dispiriting pep talk from his sadistic older brother, Rodrick (Devon Bostick), he's certain he'll quickly become the most popular kid in school. There's just one problem: Greg's best friend, Rowley (Robert Capron), hasn't quite jettisoned his elementary-school instincts. Like any good parent will do, Rowley's mom tells him to "just be himself" and he'll make friends in no time. But while Rowley is fairly comfortable in his own skin, Greg grasps for any excuse to redefine both of their images in a desperate attempt to earn the admiration of their peers. Their concepts of what it means to be cool start to clash after Greg accidentally breaks Rowley's arm, then lets his pal take the fall for something he didn't do. After going their separate ways, Rowley effortlessly manages to make new friends while every attempt Greg makes to increase his popularity ends in utter disaster. Perhaps if Greg could just take a cue from his former best pal and stop trying to be something he isn't, he'll find a way to heal some old wounds, and rekindle an important friendship. Plenty can happen in that brief yet seemingly interminable (at least at the time) period between elementary school and high school; it's a crucial season when we begin to make the decisions that gradually reveal our true personalities. Author Kinney obviously has a talent for tapping into the insecurities -- both real and imagined -- that we all had as youngsters making that first stride toward responsibility and adulthood, and screenwriters Jackie Filgo, Jeff Filgo, Jeff Judah, and Gabe Sachs do a commendable job of bringing his vision to life on the big screen. Kids will instantly recognize characters as fictional counterparts of their actual classmates, and adults will remember those archetypes from days long gone but not yet forgotten. Every school has its own mythology, and by continually drawing the story back to a piece of rancid cheese that sits festering on the playground blacktop, the writers have found a clever way to give the student body a distinct personality while simultaneously bringing the plot full circle. Maintaining the whimsical energy of his feature directorial debut, 2009's Hotel for Dogs, director Freudenthal once again coaxes some impressive performances from his young actors, making them effectively cartoonish but not entirely two-dimensional as young Greg struggles with weighty issues of honesty while reevaluating his concept of friendship. While Diary of a Wimpy Kid is hardly that type of rare movie that parents and kids will enjoy equally, it does have enough substance to remind grown-ups of what it was like to be a youngster, and enough childhood truths to help the little ones learn a few important lessons in between fits of laughter.