In order to optimize zirconium-based alloys, it is usually necessary to understand the relationships and interaction between four different types of parameters: chemical composition, manufacturing process, metallurgical characteristics, and functional properties Examples for various materials show that corrosion resistance depends on the texture and density, distribution, and composition of the precipitate particles. The precipitate composition is determined not only by the alloy chemistry, but also by other factors, such as the cooling rate from the beta phase range. It is also pointed out that some parameters can have opposite effets on nodular and uniform corrosion. Finally, the effects of some impurity elements are described, especially the effect of sulfur on creep and of chlorine on microstructure. The original paper was published by ASTM International in STP 1354, Zirconium in the Nuclear Industry: Twelfth International Symposium, 2000, pp. 3–14.