Going to co-worker's outdoor party: to dress up or not?

I would just wear a casual button-down with the brown loafers like you've suggested. I've never found polos to be "dressy" anyways... plus the button downs I own are more comfortable than my polos.

I would think anything is appropriate to be worn to an outdoor housewarming party in June... I've never heard of anybody ever requesting guests to wear certain clothing for a housewarming party and their is certainly no "proper dress etiquette" for such an unformal event. In my opinion chinos, a polo shirt and loafers are no dressier than jeans and a t-shirt. I say wear whatever you want or whatever the weather dictates. As long as you are dressed neatly and respectfully (no t-shirts with lewd sayings for example) nobody (including any possible colleagues/competitors) could say anything negative. I'd rather be comfortable than try to dress to impress and risk looking pretentious.

do you work at best buy?

i'd just wear something fun like a pair of red trousers and a nice casual sportshirt or something like that. Maybe some suede shoes? I wouldn't go for a polo, just a casual-ish button down. Gotta find the best balance between too formal and too casual, though I'd rather be on the too casual side if it's just a housewarming party.

Assuming that the blue polo shirt is navy and of a reasonably slim fit, I'd suggest you wear that one and couple it with a pair of slim-fit worsted-wool pants in some shade of grey. Shoes are nice and brown, obv.

Don't overdress...

It will stay with you forever...

It is human nature to resent people especially collleagues for looking good...

Go for a happy medium , chino/jeans with nice shirt...

Bring a jacket and if everybody is casual just leave it in the car.

Just cannot agree with this. Polo and chinos are very often acceptable as business casual dress. T-shirts and jeans are almost never.

+100

^^agree with this, in some places (say Florida) a polo shirt is "dressed up". Kind of sad but c'est la vie.

The khaki/polo is OK, but you run the risk of looking like a BestBuy guy (like someone already said) and even worse look exactly like someone else at the party. But if you have to go that way, make sure the fit is perfect. Slim fit khakis with a polo from Kent Wang.

Or do one of these. I like the one on the left. You can remove the jacket if it's too warm, but have it ready for a pretty young lady if she gets chilly when the sun goes down.

Too smart...

That is fine for a garden party or a posh B&Q , not for a colleague outdoor party...

First you post ''chinos,nice shirt, bring jacket" I post picture of that, and you say "too smart"?

Seems more than adequate, likely that dark jeans and tepee shirt will suffice.

"This group" has not been invited s don't worry and wear what you are comfortable in.

How old are your coworkers and what line of work are you in?

Housewarming for 50 year old fund managers on their new home probably looks a little different from a web designer's starter home housewarming party.