What do a pharmaceutical, polymer and solid state chemist have in common? The answer is organometallic chemistry, since progress in their diverse fields has at many times relied on this. It is a discipline which stands at the crossroads of so many branches of chemistry, with industrial applications ranging from the gram to megatonne scale. This text aims to introduce undergraduates to the utility of organotransition metal chemistry, a discipline of importance to scientists and technologists in a variety of industry sectors. The main focus will be on the reactivity of organometallic compounds of the transition metals, supported by discussion of structure and bonding and their implications. The aim, on completion of the course, is that a student should be equipped to recognize the key classes of organometallic compound, their methods of characterization, possible synthetic routes and anticipated reactivity.