The most widely accepted definition of a rookie card is a player’s first card in a nationally distributed, fully licensed major league base set. If a player appears in several base sets during that same year, all of those cards are considered rookie cards. Also, a player can only have rookie cards in one season, so any cards of that player listed as rookie cards in subsequent seasons are not true rookie cards. To clarify, here is a more comprehensive description of what makes a card a true rookie card:

• A card must appear in a base set, not an insert or parallel set.
• It must be a regular card, not part of a subset such as an all-star or league leader card. (However, if a player has no regular card in the set, but does have a special card, then that can be considered a rookie card.)
• If a player has more than one regular card in a set, the first card numerically is the rookie card.
• The set must be a major league set. Cards from minor league sets are not considered rookie cards. There are a few sets (such as Upper Deck Prospect Premieres) that have players pictured in major league uniforms, and listed as playing for major league teams, but the entire set is made up of minor league players. Rookie cards in these sets are generally considered Extended Rookie Cards (XRC).
• The appearance of any type of rookie card or first card logo or similar designation placed on a card by a manufacturer does not necessarily make a card a rookie card. The card must meet all of the criteria listed above to be considered a rookie card.

One common misconception is that a player’s rookie card must appear before or during their rookie season. A player’s rookie status as defined by Major League Baseball has no effect on whether or not a card is a rookie card. Players can have rookie cards several years before they play in a major league game (prior to 2006). A player can also have a rookie card after playing several seasons and appearing in hundreds of games.

It is also important to note that since 2006, players who have not appeared on an MLB 25 man roster have had cards where they appear in major league uniforms. The cards are released as inserts (Bowman Prospects, Bowman Draft Prospects et al.) and are therefore not considered rookie cards. I do believe that a special designation is needed for these cards, but for now these cards are not dealt with in this book.