1. A valid passport
2. A valid U.S. visa (the visa stamp in your passport should be valid beyond the date you return to the US and should have multiple entries)
3. A valid Form I-20 (check the expiration date item 5 on your I-20 and check the back of your I-20 for endorsement by the OISS Advisor).

For J-1 visa holders, you must have: 

1. A valid passport 
2. A valid U.S. visa (the visa stamp in your passport should be valid beyond the date you return to the US and should have multiple entries) 
3. A valid Form DS-2019 (check item 3 on your pink copy of DS-2019) 

Do I need a valid US visa for returning to the US if I travel to Canada or Mexico or islands adjacent? 
No, if your travel is less than 30 days. But you do need to carry the visa documents mentioned above. For citizens of some countries, you may need a visa to travel to Canada, Mexico or some of those islands. Please check their web sites for the information. If your stay is over 30 days, you must have a valid US visa. 

If my dependents want to travel separately, do they need to obtain a new I-20 or DS-2019 Form ? 
F-2 or J-2 spouses and minor children who are not accompanied by the F-1 or J-1 student or J-1 scholar must have all of the above documents, as well. You can obtain a separate Form I-20 or DS-2019 for your F-2 or J-2 dependents from the ISSO. If the dependents have never been indicated on the I-20or DS-2019, then you must first see an adviser at the OISS. 

Do I still need the visa documents to travel to Canada if I am a Canadian citizen or a landed immigrant of Canada? 
If you are a Canadian citizen, you do not need a U.S. visa to enter; however, you do need to have the endorsed I-20 or DS-2019, valid I-94, and a valid proof of citizenship and photo ID or passport if you travel by land. A passport is required when arriving in the U.S. from outside of the Western Hemisphere or by air. Please check the updated information at the U.S. Embassy website: http://www.amcits.com/canada.asp .

For landed immigrants of Canada, please check this site (http://www.amcits.com/british_commonwealth_citizen.asp) to see if you need a valid US visa.

How often should I have my I-20 endorsed by the OISS staff?