I am a 2-year varsity soccer athlete, and I was wondering if Harvard or any Ivy in general lets you just walk on and try out for the team? Thanks
Yes Harvard, and all ivy league schools, have open try-outs at the beginning of each academic year. Any student who thinks they can compete on a Division 1 team is welcome to try-out and possibly walk-on.
Keep in mind several things though: Many non income-producing sports (archery, crew, fencing, skiing, water polo, squash, sailing etc) are NOT given enough slots from the Admissions Office to fill their teams, so coaches rely on walk-ons to fill many of their slots.
However, income-producing spectator sports (football, basketball, baseball, soccer, tennis, lacrosse and hockey among them) are given large numbers of slots, so coaches pretty much fill their rosters with recruited athletes. And those coaches don’t want their recruited athletes to be unhappy and think of transferring to another college because of a lack of playing time. So coaches in those sports tend to favor and play their recruited athletes more often. For example, I know a Harvard freshman who walked-on to the baseball team. After spending two years sitting on the bench and only getting to play in the 8th or 9th inning when the team was way ahead, he quit the team and played club-baseball.
Playing on a Division 1 team is a huge time (and travel) commitment, and many students instead play a club-sport: http://recreation.gocrimson.com/recreation/club_sports/Club_Sports_Program
Since when is Ivy League soccer an “income-producing spectator sport”? (Or, for that matter, Ivy League lacrosse or tennis.)
I haven’t heard of anyone walking on to an Ivy League squash team or fencing team and getting into actual matches. You don’t need a whole lot of slots to field a team in sports like that. People can walk onto crew teams because everyone has B and C boats and lightweight boats, but you don’t see any walk-ons in the A-8.
It varies from school to school, but this from Yale: http://yaledailynews.com/blog/2011/01/27/recruitment-caps-strain-teams/
Discussing Yale is just confusing the issue. Yale’s challenge in filling the rosters is unique to Yale because Levin made the conscious decision, rightly or wrongly, to limit the number of athletic recruits to a level below its peer group.
Harvard, to the best of my knowledge, only has 6 revenue-producing sports, which are basketball (M&W), hockey (M&W), football, and men’s lacrosse. Yup, @JHS , in this case, lacrosse is income generating. Such terminology should not be confused with the NCAA definition of headcount sports (often referred to as revenue sports), which I won’t go into.
Anyway, to answer the OP: yes, Harvard lets you try out, but to @gibby 's point, this will vary by sport, and in general, walk-ons will get less playing time (if they get any).
Of course, the OP needs to get accepted first. 
With the exception of Yale women’s fencing (where having 13 walk-ons on a 14-woman roster pretty much guarantees that some compete in real bouts), and the bizarre information that Harvard lacrosse is revenue-generating (how much?) I am not convinced my earlier comment was wrong.
Sailing – Does sailing have any actual slots? I hope not! How about polo? I think there are plenty of ride-ons there.
Also note that the recruiting process is hyper competitive in some sports.
Not sure about soccer, but in my son’s spring sport, these coaches spent the summer
traveling to find players, hosted camps on campus to see players. Hundreds of kids
spend hundreds of $ to go to these camps, to be seen. By the time a recruited freshman has made
it to campus, the coach has seen him play a couple of times at least, had many conversations,
has something invested in those players. Whether that player will be on the team soph/junior year
is another matter, they have to perform, but my point is as a freshman, you are competing against
freshman who have had more face time in front of the coach than you. If you are a superior player,
hopefully you have a good tryout, but you have to be better than, not same as the recruits.
Recruited players themselves went through considerable effort to be there, the coach knows that and
would assume a higher level of commitment in return from most of those players. Walk on either did
not make the effort in the recruitment process or maybe just was a late bloomer and grew/improved significantly
during senior year of HS after the recruiting process was over
(in which case it makes a lot of sense to try and walk on).
As far as the commitment, Harvard’s location near many of the other Ivies I think would mean a bit less
travel time than let’s say Cornell which is remote and isolated from all the other Ivies. But practice time
would be MUCH more than a club team.
Well, water polo had 6 recruited athletes in 2014. I would imagine sailing receives about the same number of slots: http://www.collegiatewaterpolo.org/varsity/news/2014-15/051615HarvardMenRecruits
I think @JHS was referring to pony polo, not water polo. 
Regardless, polo is a club sport, so there are no slots.
Probably high. My guess is around 3, but it’s pretty academic, since it has nothing to do with the OP’s question, and unless someone asks the AD, we’re only guessing.
I personally know of 2 players on the Princeton team. Walks ons who got playing time.
I know a Princeton walk-on too who gets playing time.
Yes, there is one. He’s identified on their website. Princeton recently changed coaches, and was the weakest men’s squash team in the Ivy League last year. So the fact that Princeton has one walk-on who plays varsity matches regularly and another who has played a couple over multiple years does not mean that it’s common for Ivy League squash walk-ons to get varsity matches.
I wouldn’t expect that you would have heard of these cases but they do exist, and not exclusively at Yale. It has certainly occurred at Princeton.
I’ve asked athletes at Princeton and Harvard to confirm this assertion and am told that while most and possibly all coaches are open to walk on candidates, there is no beginning of year, campus wide, open try-out period for the various sports.
Out of curiosity I just had a look at the mens squash rosters at Harvard, Yale, Brown, Penn, Cornell, Dartmouth and Columbia. With the exception of Harvard, there were at least 1-3 spots on each of the teams that were walk-ons. Its easy to tell who was a walk-on vs those who were recruited by going to their US Squash profile.
So I definitely disagree with the statement that it is uncommon to get playing time as a walk-on.
Just posted yesterday:
http://www.gocolumbialions.com/ViewArticle.dbml?DB_OEM_ID=9600&ATCLID=211158016