Summary
Abhidhamma is the 3rd and last part of the Buddhist Pāli Canon. This book is meant as an introduction to the various concepts presented in the seven books of the Abhidhamma.

Contents of this online book
The full text of the Introducing Buddhist Abhidhamma in English is available here and publically accesible (free to read online). Of course, it is recommend buying the book so you get the latest edition.

Read pages on
INTRODUCING BUDDHIST ABHIDHAMMA, BOOK I, Part 1 – Abhidhamma, introduction
INTRODUCING BUDDHIST ABHIDHAMMA, BOOK I, PART 2 – Meditation
INTRODUCING BUDDHIST ABHIDHAMMA, BOOK II – Concentration
INTRODUCING BUDDHIST ABHIDHAMMA, BOOK III – Miscellaneous Papers

Dedication
This book is gratefully dedicated to my two Teachers, 
The Revd. U Nagasena, who was formerly Saya U Ba Gyaw,U Thein Nyun who assisted U Narada (Mula Patthana Sayādaw) in the translation of Dhātu Kathā (Discourse on Elements), and Patthana (Conditional Relations), being the third and seventh Treatises of the Abhidhamma. He is the Author of many articles on Buddhism, such as, ’Approach to Practical Buddhism’, ’The 4 Noble Truths’, ’Mind the Mind’.

Original was printed and published March 1979
by U Myint Maung, Assistant Director,
Regd: No ( 02405/02527 ), at Religious Affairs Dept. Press,
Yegu, Kabā-Aye P.O., Rangoon, BURMA.
Digitalised July 1993 by Wolfgang Greger, Chiang Mai, Thailand