Science Fiction; Coming-of-Age; Dystopian Literature
Let's get the obvious one out of the way first. Childhood's End is card-carrying member of the science fiction genre. In fact, Clarke is part of a group of authors—including Robert Heinlein, Isaac Asimov, and others—who are credited with basically inventing the genre as we know it.
But what really makes the novel science fiction is the way science and philosophy are woven into the story. The advanced gadgets aboard Karellen's ship may provide nifty science toys for the story to play with, but it's what those gadgets represent that makes this tale science fiction.
For example, in the world of the novel, Karellen's technology and the mere existence of an alien species puts a strain on the beliefs held by religious people, and "within a few days, all of mankind's multitudinous messiahs had lost their divinity" (6.31). See—it's not the simple addition of science to the story that makes this book sci-fi, it's the exploration of the implications this science brings to the world with it.
Dystopia 'R Us
Clarke plays with the genre of dystopia a bit in this novel, too. Most dystopian futures are obviously awful places to live—the poor are poor, a select group controls everyone else, and freedoms are a long lost memory. Lois Lowry's The Giver provides a pretty good example of what we're talking about here.
In Childhood's End, everything isn't so obviously dystopian. In fact, at first glance, things are just peachy. Everybody has their needs meet, there is no war, and people scoot around in flying cars. Flying cars! That seems pretty swell to us.
Yet everything is not so hunky-dory. As things get better and better for mankind, things get less and less Utopian. Instead, characters like Jan Rodricks and Ben Salomon have to deal with "the supreme enemy of all Utopias—boredom" (6.36). Oops.
Although only noticed by a few, this ennui spreads throughout society and leads to stagnation in art and human culture. The novel suggests the end to hunger, disease, and violent crime is not something to sneer at, but that these things are on some level needed to enliven other critical parts of human existence, namely art and culture.
So, the novel is painted utopia on the surface, but there's a dystopian core at the heart of it.
Oh, Grow Up Already
Finally, Childhood's End is a coming-of-age story. Instead of being a coming-of-age tale for a single person, though, as is usually the case, it's about the entire human race growing up. Like a child trying to find its own path despite overbearing parents, this novel is about humanity trying to find their own way despite the interference of the Overlords. Sure, some people are content to live under the Overlords' thumbs, but others, such as Jan and George, need something more.
In the end, humanity does grow up and evolve out of their childhood state. Whether that's a good thing or a bad thing… well, pop over to our "What's Up with the Ending?" section to open that can-o-questions.