In this book, Islamic calligraphy is defined and explored by focusing on its application in mosques. It starts by emphasizing the significance of Islamic monumental inscriptions, the theory and the historical backdrop. It also provides accounts of how Islamic Calligraphy was esteemed and applied by early Muslim societies. The view of Shariah and the stand of Muslim schools of thought towards decoration in mosques is discussed to determine their references and grounds of their position. Some most common calligraphic inscriptions materials such as stone carvings, tile decorations and woodcarvings are elucidated. To study the calligraphy applications, a number of prominent mosques from three different countries are selected. These countries are Egypt, Turkey and Malaysia. The selected mosques of Egypt are the AlAzhar Mosque, Sultan Hassan Mosque and Muhammad al Kabir Mosque. From Turkey are the Sultan Ahmad Mosque, Suleymaniye Mosque and Bursa Ulu Cami, whilst the Malaysia mosques are those selected from within and around Kuala Lumpur namely the Putra Mosque, Putra Jaya, Wilayah Persekutuan Mosque, Kuala Lumpur and the Sultan Salahuddin Abdul Aziz Shah Mosque Shah Alam, Selangor. It analyzes the calligraphies that are located in the mosques interior or exterior as well as its elements such as the prayer niche (mihrab), the pulpit (minbar), the calltoprayer tower (minaret) and the dome (qubbah). Finally, the book emphasizes the most popular written style of calligraphy and the most frequent themes in mosques, followed by their meanings and rationale behind the selection.