Round trip required?

Coming down Saturday On a 1 way ticket. Didn't make a return reservation due to an Easter "glitch", so return is a little bit up in the air. But planning mid to late April. A friend advised me that a round trip ticket is required before an airline will allow you to travel. Correct or not?

Incorrect. At least for México. I have heard of other countries that require a round-trip ticket such as Fiji but you would have to verify this information. I routinely bomb down to Mexico with one way tickets.