Markus Schrenk (Köln) gives a talk at the MCMP/MCTS Workshop on Laws of Nature (17 December, 2012) titled "Trouble with Properties for Better Best Systems". Abstract: In Lewis' original best system account, the mosaic of point-sized, intrinsic, quiddistic, perfectly natural, fundamental properties is the ultimate material on which everything else, laws of nature in particular, supervenes. While better best system competitions (BBSCs) for different, separate special science property sets aim to apply the same mechanism as Lewis's to get the laws from the distributions of properties (balancing simplicity, strength and fit) it is not so clear: (i) which features properties of the special science have (they are clearly not fundamental, maybe not natural but also not-quiddistic, etc.), (ii) in which kind of entities they are instantiated (clearly not singular space-time points), (iii) how BBSCs deal with vague and extensionless properties, (iv) and what the boundaries are for the different sets of properties which BBSCs take as raw material for allegedly separate competitions. This paper will show that (i) - (iv) are not easy to answer for (us) better best system advocates.