There are some events such as drinks in the office after work, where it is clearly inappropriate to bring a significant other, but others such as holiday parties where it is perfectly acceptable. I work for a small company, and would like my SO to get to know my coworkers, but at the same time do not want to interfere with company bonding by bringing in an outsider if they are not welcome. Is there a good rule of thumb for determining which work related social events are appropriate to bring an SO to?
Here are some rules of thumb:
Always appropriate if put on the invite - Holiday parties, big award ceremonies - anything with a formal invite will usually clarify.
For RVSP events - if you have, say, an informal holiday party, but with a coordinator asking fo RSVPs, it never hurts to ask the coordinator whether other folks are bringing SOs.
For company-sponsored events - if it's come one/come all company sponsored, ask the boss or skip it - since the company is paying the bill, spouses add expense - so either the company is willing to double the headcount or it isn't.
For small groups - for team/department informal stuff - ask the gang - if you like these people well enough to introduce them to your SO, you ought to feel comfortable enough with them to ask "is anyone else bringing an SO?
I've often found there's a sliding scale in a few different dimensions:
Day/Night - at least in big companies in the US, daytime events almost never involve SOs, night time events might.
Big vs. Small Company/Group - the smaller the group or company, the less formal, for the most part - so violating an unspoken rule is less of a faux pas. Also, in a big group/company, EVERYONE bringing a spouse poses a major logistical challenge. Example - a 4 person startup where 2/4 people have SOs means the outing changes from 4 people to 6 - it won't take any extra effort. Compare to - a 10 person team where 8 people have SOs, that changes your average restaraunt booking to something that can be done that afternoon, to something requiring 2-3 days of advanced notice. 100->150 people can mean renting a different function space.
Informal vs. formal - when a company has planned something like team building, or other structured event, it will usually be explicit and unchangeable. When 5 people look at each other say "shall we grab a beer?" you can usually follow it up with "hey, my SO works 10 minutes away, mind if she/he joins us?"
Age of group - when a group is largely single or child free, the norms are usually more easy going. The logistics of established families means that people with kids need babysitters and so forth. So in a group past a certain age, the unspoken "norm" can be that it's coworkers only.
Location - I was really surprised when changing jobs recently how much different the after work culture was - and I attribute it largely to the change in location - downtown in a city, the party can be held in a bar and pretty much anyone who can make it there is welcome. There's a big after-work culture across many businesses in the district, so folks meet up with former collegues, friends, and SOs without the exclusivity of a single office. In the suburbs, there seemed to be a greater overhead - the local industrial park did not have a favorite after-work location, nor could any venue hold many people - so if folks went out, the group size stayed under 10 people.
Activity - if you're doing an informal activity, the one thing that seems universally uncool is to bring an SO that hates the activity. If you all go bowling and your SO hates bowling, don't bring 'em. Seems obvious, but I think everyone has a story of the person with "that girlfriend/that boyfriend" who sat around the whole night hating every minute. If it turns out that your SO is hating the party, be cool and take 'em home.
There is only one real way to find out if it's OK to bring SOs (which I assume you mean Significant Other, not Stack Overflow) - ask the person organizing the event. If it's a big event, ask your boss. Companies vary, events vary, local cultures vary. Asking is always the way to go. Asking won't make you look bad. (Turning up unexpectedly with your SO however might).
If you want your SO to get to know your coworkers, invite them all for a drink after work and invite your SO too. If it's out of work, and you organized it, then you set the rules.
All invites where SOs are encouraged to come will specifically have that written. Imagine you were organizing the event/outing and you wanted the employees to bring their SOs would you leave this important information out of the invite ? My rule of thumb : If it is not there in the invite, don't bring the SO.
If it's on company property, unless SO's are specifically invited (holiday party, ribbon cutting, etc.) I would not bring my SO. People have an expectation at the workplace that employees will be there. Further, many companies have sign in policies, or other physical security measures that make it inappropriate for non-employees to simply enter and socialize.
If it's offsite, I would say that's fair game. People do not have the same expectations, and you're far less likely of interfering with people's work or running afoul of HR issues.
As mentioned by others above, the appropriateness is ultimately determined by who is controlling the event.
So, if you really want your SO to meet your coworkers, make your own event. Setup a light social event like a picnic, barbecue or something seasonally appropriate and invite co-workers and their SOs, so everyone can get to know each other.