Hi Ron, My wife has her H4 visa stamp on her passport(done in Feb 2013 in India) and she entered USA on that H4 visa. Her I-94 has class of admission as H4 and is valid till July 2016. However, her H4 visa has expired earlier this year. Also, last year she did a COS from H4 to H1B and currently is working on H1B. We are planning to go to Mexico for getting her H4 visa stamping done there and return on H4 visa. Hope she is eligible to go to Mexico for getting her H4 visa stamping. Thanks!