No discussion of concrete inspection would be complete without considering the basic components that go into the finished product. We know that the components of concrete- aggregates, cement, water and perhaps some admixtures- are mixed together according to a formula. This mix is placed in a form, generally around reinforcing steel, and after it hardens the surface is cured, perhaps by spraying with a curing compound. The question is: how do we go about approving these various materials? Also, how do we know that the aggregates don't have soft particles which can reduce the concrete strength, that the cement has been properly manufactured to set when we want it to or that the steel is the specified grade? These questions are the subject of this article. Let us trace the steps leading from the raw material to the finished concrete product. The first step is to evaluate and approve the sources of materials. Once the suppliers have shown that they can produce the raw materials required for the concrete desired, the nest step is sampling of the materials. Sampling should not be underestimated since it is necessary to validate the third step in the process, testing of materials. Fortunately testing is fairly will described and prescribed in ACI and ASTM publications. The key is not necessarily the method of test but the type and number of test necessary for approval of materials. The final step prior to approval of materials is proper evaluation of the test results. Only after all of these steps have been taken can the basic components of concrete be truly approved for their intended use. Only after the entire process- approval of sources, sampling, testing, and evaluation- can approval of the materials used for the finished concrete structure be truly given. Typically, the adequacy of each step of this process will provide a higher and higher probability that the concrete will be adequate.