In 1969, the DUPLO system went on sale. This was a newly developed system, targeted towards younger children; DUPLO bricks are much larger than LEGO bricks, making them safer for very young children, but the two systems are compatible: LEGO bricks can be fitted neatly onto DUPLO bricks, making the transition to the LEGO system easily made as children outgrow their DUPLO bricks.
- DUPLO Town, includes the ever popular farm and zoo sets, also known as LEGO Ville.
- DUPLO Trains 1983-present
- DUPLO Toolo 1992-1996
- Little Forest Friends 1999-2000
- DUPLO Dolls 2001
- DUPLO Castle 2004-2006
- Princess Castle 2005-2007
- DUPLO Pirates 2006
Several DUPLO subthemes have been produced in conjunction with popular children's animated television programs or other corporate entities. Animated characters typically appear in sets based on episodes of the particular series.
- Winnie the Pooh 1999-2001
- Bob the Builder 2001 - 2006
- Little Robots 2003-2004 (UK, Australia only)
- Ferrari 2004
- Dora the Explorer 2004
- Thomas the Tank Engine 2005 - 2009
- Disney Princess 2012