Python is a modern computer language whose use in the atmospheric and oceanic sciences (AOS) is growing by leaps and bounds. Yet, while many excellent resources exist for learning Python, there have not been any resources specifically written for the AOS user. This book is a hands-on introduction to Python written for AOS researchers, graduate students, and advanced undergraduates who are new to Python (seasoned Python users will find the book of limited use). It focuses not on computer science but on how Python can help AOS users do AOS work. It is not a reference manual but a mini-course. We take a gentle approach to learning Python but do not aim to teach programming; readers should already know the basics of programming in another language. A color PDF version (with active hyperlinks) of this book is also available from the Lulu Marketplace. Note: Enthought Python Distribution (EPD) users should see the book's website (http: //www.johnny-lin.com/pyintro) for an errata workaround specific to EPD.