An accessible text for students, researchers, and practitioners in the general area of Signal Processing, is an expanded edition of the text “Introduction to Spectral Analysis” by the same authors (Prentice-Hall, 1997). A host of new complements and exercises along with an appendix on model order selection have been included in the book to make it a more up-to-date and useful text as well as a more self-contained learning tool for a diversity of students and researchers. The text presents an introduction to spectral analysis that is designed for either course use or self-study. Clear and concise in approach, it covers both classical and modern approaches of spectral analysis. Topics covered include nonparametric spectrum analysis (both periodogram-based approaches and filter-bank approaches), parametric spectral analysis using rational spectral models (AR, MA, and ARMA models), parametric methods for line spectra, and spatial (array) signal processing. Analytical and MATLAB-based computer exercises are included to develop both analytical skills and hands-on experience.