NGC 346 is an extremely young and compact star cluster, which excites  
the largest and brightest HII region (N66) in the Small Magellanic Cloud.
The ionizing cluster contains a major fraction of the  O stars known in  
the entire galaxy. Ground based narrow-band images show abundance of  
dust and compact, embedded clusters, surrounding the main ionizing 
cluster, suggesting the presence of a second stellar generation,  
triggered by the outflows from the most massive stars, as observed in  
30 Doradus.
While the brightest stellar population of NGC 346 has been well  
investigated in the past 20 years, we have very few informations on the  
fainter cluster stellar content. The exquisite resolutive power of the  
Hubble Space Telescope now allowed us to study in detail its stellar  
content down to sub-solar masses. This study has revealed a rich  
populations of pre-Main Sequence stars, whose masses range between 3  
and 0.5 solar masses, and strong evidence of ongoing star formation.