This chapter analyses the problems associated with the Avestan language. A consensus has been reached both in the analysis of individual Avestan word-forms and in the interpretation of the texts which depends on this analysis. However, the Avestan tradition still conceals many a riddle to be solved by later generations of investigators. In principle, this may be due to three well-known reasons: Firstly, we have to take into account the fact that the Avestan corpus is rather small: less than 1,700,000 characters if arranged in a plain text format. The second reason why we cannot expect to find ad hoc solutions to the problems offered by the Avestan tradition is the fact that we do not dispose of an immediate descendant of the Avestan language in Middle and New Iranian times. The third reason why we are still far from being able to solve all the riddles posed by the Avestan tradition lies in the circumstances of the transmission of the Avestan texts themselves. The chapter suggests that further progress in Avestan studies can only be achieved by taking a closer look at the similarities and interdependencies which connect the Avestan language with Vedic Old lndic.