B1 Business Visa

Eligibility Requirements

Visit is less than one year
Cannot be on payroll
May receive per diem/travel, nothing beyond that such as honorarium
Best visa type for workshops/seminars.
If doing research or “gaining knowledge,” it becomes less clear if the B is appropriate (Regulations are not clear so officials interpret differently; Funds from home institution helps, illustrates collaboration)

Visitor should contact Consulate to confirm B is acceptable for visit (some are good at advising, others will not do it)
Visa Interview – Invitation letter from host required
B visas can be issued for up to 10 years in which case the visitor may already have the stamp & not need an interview
Period of stay reflected by I-94 card

Cannot engage in employment (cannot be on payroll or considered to have gainful employment in the U.S. This is why visits that are collaborative in nature are a little more predictable and there are fewer concerns/issues in obtaining visa stamp and entering U.S.)
Stay cannot exceed 1 year

This visa type can be less predictable than a J1. We have had a few denials at the port of entry. I advise visitors of the risk. A lot of the uncertainty revolves around the visit being interpreted as "gainful employment." Visits that we funding and are longer than 90 days seem to be at higher risk of problems.
A "carry letter" is recommended. This is an invitation letter with the financial information omitted intended for the visitor to carry with them when entering the U.S. This reduced the risk of the visit being interpreted as "gainful employment."
No documents are needed from UCAR/NCAR aside from invitation & carry letters.
If you are providing any funds beyond travel/living expenses, this visa is not appropriate and a J1 is required.
There are no strict medical insurance requirements for those on B1 visas as there are for those on J1 visas.
http://travel.state.gov/visa/temp/types/types_1262.html