Works with the Uno! This prototyping shield is the best out there (well, we think so, at least). It works with UNO, NG, Diecimila and Duemilanove Arduinos. You can use it with a Leonardo but it will not break out the hardware SPI pins (theyre only on the ISP connector underneath) or the IOREF/SDA/SCL pins. However, the SDA/SCL pins on the Leonardo are also on digital #2 and #3 so you can still use them by connecting to #2 and #3.