This installer is for 64 bit systems only. Any application/executable created with this version of the IDE will only run on 64 bit systems.
If you want to create applications that can run on 32bit and 64 bit, then you should download and install the "Window 32bits" Lazarus IDE.

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For additional information visit our homepage, forum, wiki, and FAQ:
http://forum.lazarus.freepascal.org/
http://wiki.lazarus.freepascal.org/Lazarus_Faq