What is role of speaking in tongues in Assemblies of God denomination? A previous question was answered listing perhaps only one denomination, and it wasn't AOG, that held speaking in tongues as sign of spiritual maturity. Does the Assemblies of God group speak in tongues?
Assemblies of God strongly believe and encourage speaking in tongues. It is considered as  the physical evidence of receiving the Holy Spirit. 

This site   mentions about this matter. It says,


  The baptism of believers in the Holy Spirit is witnessed by the
  initial physical sign of speaking with other tongues as the Spirit of
  God gives them utterance. (Acts 2:4) 
  
  The speaking in tongues in this instance is the
  same in essence as the gift of tongues, but is different in purpose
  and use.
  ( 1 Corinthians 12:4-10 , 1 Corinthians 12:28 )


The preachers in AG churches many times encourage their members to speak in tongues and sometimes it became a burden to some of the members who are not speaking in tongues, but this is some exceptional case. Some preachers take less importance to tongues but not diminish it. The worship in AG churches are all centered around inviting the Holy Spirit, singing, praying and speaking in tongues. Worship services are mostly lively and sometimes  noisy because many people speak in tongues loudly.