The addition of immunocytochemical staining procedures to a diagnostic cytology service enables greater specificity of interpretation for many common disease conditions, especially neoplastic diseases. However, well-tested immunohistochemical techniques may require modification for cytologic specimens, and other considerations are necessary when working with air-dried cells. In this article, we describe our experience in evaluating options for sample transport and handling, and discuss methods for obtaining control cells from a variety of tissues for use in immunocytochemical staining. Important immunocytochemical principles and techniques, including fixation, antigen retrieval, and use of primary and secondary antibodies in manual and automated staining systems are described as used in our laboratory for cytologic specimens. Although we emphasize methods relevant to diagnostic laboratories receiving samples from external clients, the information is also applicable to any laboratory interested in adding or enhancing immunocytochemical services.