When developing new MEMS devices there are several decisions which have to be made. The first of these is which technology to use. Today there are a range of silicon based micromachining technologies available. In addition to backside bulk micromachining and surface micromachining, new processes available include epi-micromachining and deep plasma etching. These are all silicon based technologies. New processes using alternative materials have also been developed and these include processes such as LIGA and SU-8. The decision of which process to use is often based on the equipment available and the type of structure to be fabricated. The second question is often more difficult, and that is whether or not to integrate. The integration of sensor with electronics can present a number of advantages, in particular when dealing with small signals or noisy environments. However, there are many applications where environmental factor ensure that the electronics will not function correctly. It is also important to ensure that the processing used for the MEMS devices does not adversely affect the electronics. MEMS device scan be fabricated as pre- or post-processing modules, or integrated within standard processing. In each of these optics on the compatibility issues such as non-contamination of the processing line and thermal budget have to be considered. Furthermore the potential drop in yield of the total devices has to be weighed up against the advantages. This paper will examine these decision and how the different aspects of technology and applications effect the choices concerning whether or not to integrate.