One of the most common, and annoying, questions homeschoolers get asked is, "What about socialization?" Despite the amazing growth of homeschooling in the last decade or so, many non-homeschoolers still retain the image of the shut-away family who rarely ventures out-of-doors or encounters anyone they don't live with. There's a perception that proper socialization requires school, that children won't learn how to interact with their peers unless they spend six to eight hours a day, five days a week, cooped up with a random sampling of them.
I often point out that the type of socialization one encounters in the school setting is actually quite false and unnatural. When, in your life, will you be segregated with people more or less exactly your age, to the exclusion of all others? Even in college you begin to encounter a more mixed group of people: older students, adults who are continuing their education, and the like. But that slight increase in the diversity of ages is nothing compared to what you will encounter in the workforce; few places of business hire people in their early twenties in large groups.
As to the teaching of basic social skills, I'd argue that these are easier to instill at home than at school. It may be the teacher's job to make the students in her care behave, sit down, be quiet, and focus on the lesson at hand (though in many schools teachers struggle just to accomplish this much), but it certainly isn't the teacher's job to teach children to greet adults politely, to open and hold doors for each other, to eat with attention to table manners, to be generous, kind, thoughtful, concerned, cheerful, hygienic, trustworthy, and diligent. Some exceptionally good teachers may inspire their students to learn these behaviors, but it's really the parents' job to teach these things, and to teach them primarily by example.
Still, having attended many schools in my educational career, I have to admit that there is a type of socialization my homeschooled children will not experience until they are much older. It is the one form of socialization schools are really good at, and which is sometimes encountered when you've left school behind. This is the type of social structure known as the clique.
The clique is popularly associated with high schools and teenagers, but it is being found among younger and younger groups of students in the present day. In fact, I'd say that the average school contains many different cliques, and woe to the child who doesn't manage to fit into at least one of them! Most of us remember the different cliques: the popular kids, the athletic kids, the artistic kids, the troublemakers, the smart kids, the 'losers,' and so on. But even the lowest-ranked clique was 'higher' in most schools' social strata than those kids who were outside of them all. In the merciless cruelty schoolchildren are capable of, some kids were permanently excluded from the social world for the 'crime' of not fitting in.
Sadly, adults sometimes exhibit this behavior, as well. Homeschooled children may get to skip the cliques of school just to encounter this sort of thing later in life. Some of them may experience it in the workplace, when as Catholics with strong family values they don't 'fit in' with the latest politically-correct agenda of the corporation; some of them may encounter it at their parish, when traditional-minded Catholics may not 'fit in' with the more vocal, liberal laity who run every committee and faint in horror at the sound of Latin; some of them, sadly enough, may find it in Catholic homeschool groups, where a particular activity or suggestion doesn't 'fit in' with "the way we've been doing things for years."
Cliques may be a part of life, but they're a nasty example of our fallen world, not an ideal of socialization to hold up to our children. I don't think it's necessary to send our children to school to learn how to socialize in this way, any more than I think it's necessary to send them to school to expand their grasp and use of common expletives. Some kinds of behaviors don't deserve to be taught.