The monograph discusses the synthesis and analysis of adaptive algorithms for single and diversity reception of signals in channels with multipath and complex exposure to a set of fluctuating and narrowband interference with incomplete a priori information. Adaptation is seen as a means of overcoming a priori uncertainty about the properties of signals, channels, and interference. The content of the monograph (except for review paragraphs 1.1 and 6.1) consists of the author's original research results. The book is intended for senior students, graduate students, scientists and research engineers involved in the research and development of telecommunications systems.