The First-Year Player Draft (or "MLB Rule 4 Draft") is held annually over a three-day period in June.
There are 40 rounds (there were 50 rounds prior to 2012), and draft order is based upon the inverse order of winning percentages from the previous season. If the winning percentages of two or more clubs are the same, the club with the lowest winning percentage from the previous season picks first. If two or more clubs are still tied, league standings from two years back (or three years back, four years back, etc) are used to break the tie.
Article XX-B Free-Agent Compensation draft picks are slotted in the Supplemental 1st Round of the MLB Rule 4 Draft pick (between the 1st and 2nd rounds), and the 12 Competitive Balance Rule 4 Draft picks that are awarded annually are slotted in two groups (six of the Competitive Balance picks are slotted immediately after the Article XX-B Free-Agent Compensation draft picks in the Supplemental 1st Round, and the other six Competitive Balance picks are slotted in the Supplemental 2nd Round between the 2nd and 3rd rounds).