The social question comes up, generally first or second[1], when people find out that my wife and I chose the homeschooling route. We live in the Bay area, which is pretty urban, and there is a pretty vibrant homeschooling community.
One of the activities my kids participated in was the Riekes Nature Studies program. Once a week a group of about 20 similarly aged students would spend all day (9AM to 3PM) at Huddart Park (a wooded nature park near Woodside) and study different aspects of the park. They would count bird populations, identify tracks, identify plants and their properties, relationships between water and plants and animals, Etc. They also did camp trips to nearby places, once as far as Death Valley. All the while teaching camaraderie, respect, and how to socialize with your peers. We also did a 'science roundabout' with 6 other families home schooling where all of the kids would go to one of the parents houses for a half day of science curriculum. We had a Doctor, a couple of engineers, a couple of Chemists, and a biologist I believe. Two days a week. each day one of the parents would host the group, so while the group met twice a week each parent saw them once every three weeks. That was a good amount of time to work up a concept/lab for the next group session. They also participated in a bunch of other activities as group, whether it was Church related or softball or scouts.
What they didn't have to deal with is bullies in middle school and uninterested adult supervision. Or being traumatized by kids that were attempting to establish dominance through social stratification. When one of those negative patterns surfaced in one of the kids in our cohort it was pretty clear pretty quickly that either they could learn to be an adult about this stuff or not participate. That is really effective on 10 and 11 year olds who are trying to figure this stuff out.
[1] In my area the other question that competes with this one is "Can my kid get into a good university if they have been home schooled?" and the answer is yes, and sometimes more easily if they have a lot of activities and projects.
[2] http://www.riekes.org/nature/