Zambian culture is very traditional and in the rural areas you will see nearly all the women wearing the customary chitengi (long skirt). As with most traditional cultures it is not a good idea for women to walk around in revealing clothing - especially showing your legs (above the knee) - and you will earn more respect the more formally you dress.
As part of GRI’s Volunteer Programme you may be visiting the surrounding chiefdoms, interacting with community members and potentially meeting Honourable Chiefs. You will be briefed on how to behave in such situations, however in general you should be aware of and respect the local customs.
Zambia is composed of many different tribes, rich with differing traditions and ceremonies. If you have an opportunity at the end of your volunteer programme it is worth taking some time to explore the region and see what treasures Zambia has to offer.