You need to download and install all three packages fpc, fpc-src and lazarus. fpc - the Compiler, some command line tools, base units and non visual components like database access fpcsrc - the sources of fpc and its packages, needed for code browsing lazarus - the IDE, visual components and help files For an overview what changed from previous 1.2 Version (includes incompatibilities with earlier versions) see: - http://wiki.lazarus.freepascal.org/Lazarus_1.2_fixes_branch - http://wiki.lazarus.freepascal.org/User_Changes_2.6.4 For an overview what changed from previous 1.0 Versions (includes incompatibilities with earlier versions) see: http://wiki.freepascal.org/Lazarus_1.2.0_release_notes