Classical Be stars – i.e. non-supergiants B stars with some emission – are very intriguing objects. They represent nearly 20% of B stars. Emission originates in a circumstellar envelope more or less concentrated around the equator, and whose origin is so far unexplained. Fast rotational velocity of Be stars does not attain break-up velocity and an additional process is needed to account for circumstellar region formation. Non-radial pulsations in Be stars were discovered for more than twenty years and asteroseismology is the only way to study the internal structure of these stars. It may also provide some clues to understand the “Be phenomenon”. The opportunity to observe Be stars during long times, without daily interruption, is specially important, considering non-radial pulsation periods of Be stars.