Do I have to be a good neighbor?

I took a job in a new department at my company. This new department shares an office space with another department. The position I accepted was vacant for an entire year before I came along. The Administrative assistant in the other department works part-time and while she was here did a lot of work for my supervisor. I should add, this administrative assistant isn't a very good employee, she's frequently absent and late for work every single day. Her department is sort of expecting that I keep up with the routine of juggling duties for both areas. However, I refused. I feel that I wasn't apprised of these "responsibilities" and shouldn't be asked nor expected to work for another department for free. Am I wrong here?

Not at all. If it was not presented to you during your interview or in writing in a job description, then it is the other departments responsibility to hire someone to fill those shoes. You could be a "good neighbor" by requesting to be compensated for your time. Or at least help once in a while if someone is in a bind but don't let them take advantage of you.
When I say compensated, it could be in additional pay or a lunch, dinner, gift certificates for you and guest/spouse to use, etc.

Not in this case, no. If it is not assigned to you, you don;t do it

Sure, do it, but ask that your compensation be adjusted before taking on additional work.

no your exactly right here. You were getting to much weight on your shoulders that you didn't deserve. you should take it up with someone.

Some times its best to keep quiet and work as hard as possible . you may be being watched... Some day they may say your not working hard enough

no. if it isn't your job, then you should not be forced to do it.

What you need to do is speak to your immediate supervisor about the situation and find out what he/she thinks about it. Once you have that information, you can make a better more informed decision.

You should read your job description, and be sure what it says about support for other departments. Then speak with your supervisor/manager. Tell them honestly what problems doing someone else's work cause you. They may be unaware of the situation, or trying to do a favor to the other department manager. See if you can work out a deal with them. If your job doesn't keep you busy 8 hours a day, and the extra work is at the same job level or lower than yours, you may be stuck doing the work unless/until the other admin. returns to full time, or they hire someone else.

Because the other department's administrative assistant covered a portion of your current positions work load for one year they may not think that covering for her is such a big deal. Especially since that employee is present sometimes even though she is always late. The likely concept is "Turn about is fair play." Rejecting the work does not reflect well on you and your willingness to be a team player.

You could either do it or don't. But by refusing to do something that your employer asks of you - looks real bad, and don't be suprised if your let go.

In this situation I can only say, you are an employee and took the job to take assignments and/or tasks for your company. In this case, an assignment in which your company wants you to do something for a completely different department; it is your duty to fulfill your assignment. Neglecting to do so can look bad and may cause a release for your employment.

I understand that some situations may seem a little off or completely off of your department duties, but a company is a team and a team isn't a team without all of its team members working together.

As for the other employee, it does not involve you, don't worry about his/her absence or tardiness. Usually big corporate companies don't mind a person being late (as long as it is not that often); they mind when an employee can not do something for them.

-small restaurants and clothing stores usually worry about time
-corporate companies usually allow you to make up time and don't mind tardiness, just as long as you complete your duties.
-departments usually work together so that they optimize company achievements and reduce work load.

I think it depends on what you want from your job. Do you just want to clock in, clock out, collect your paycheck, stay in the same job forever? Then, by all means, refuse the work.

But if you want to grow with this company, you have to put aside your feelings about this admin and find a way to make it work. If you feel that you're being improperly compensated, outline the reasons why and sit down with the decision makers and convince them to give you a raise. If your objection is that this other lady isn't carrying her weight, sit down with the supervisor and address your specific concerns.

Show your professionalism and show them that you're an invaluable member of the team. Show them that your being there makes the workplace a better place.

Good luck!

No, you're not wrong. You shouldn't be expected to do someone else's job while THEY are being compensated for it.