Multisample Anti-Aliasing (MSAA) is supported by the XNA Framework: See MSDN: Enabling Antialiasing (Multisampling).

However, MSAA is not compatible with the light pre-pass renderer ("deferred lighting") as implemented in the examples. It is recommended to use Fast Approximate Anti-Aliasing (FXAA) or Enhanced Subpixel Morphological Anti-Aliasing (SMAA) instead.

Fast Approximate Anti-Aliasing (FXAA) is implemented as a post-process filter. See FxaaFilter.

Enhanced Subpixel Morphological Anti-Aliasing (SMAA) is implemented as a post-process filter. See SmaaFilter.