What is the baptism requirement for becoming a Mennonite? Historically, Mennonites and other Anabaptists practiced adult re-baptism when a Catholic or Lutheran converted.  This got them in a lot of hot water at the time.

As a long-time member of a General Conference Mennonite Church (now the Mennonite Church USA), and a current member of a Mennonite Brethren church, my impression is that when a Catholic (or other person baptized as an infant) becomes a Mennonite, they are generally given the option of re-baptism, but it's not considered a requirement.  But admittedly, this doesn't happen very often in the U.S.

And in Mexico, where practically everyone is born Catholic (and therefore baptized as an infant), re-baptism seems quite common; but in Mexico the Catholic and protestant churches are often quite at odds with each other (Mexican Catholics think "Christian" is a dirty word).

So my question is:  What are the official rules among Mennonite churches regarding re-baptism of new members of the Mennonite church?
A few things based on my own experience in the Ontario Conference of Mennonite Brethren.

It is a matter of doctrine that only those baptized 'of the age of accountability' are considered validly baptized. Baptisms of infants are not considered valid. 

However individual churches are, I believe, able to set their own rules about whether baptism is required, and for what. The norm is that baptism is required for membership; but in many Mennonite churches people can be very active participants for a long time, even serve in leadership positions, without becoming formal members, and thus without being baptized (i.e. without being rebaptized if you were baptized as an infant). That was certainly true in my case.

So in short: if you were baptized as an infant you are considered not baptized: however that may not be much of a restriction.