There’s a good plugin for that, something like Restrict Group Creation.  If somebody doesn’t beat me to it, I’ll dig up the link.
EDIT:  Here you go:  https://buddypress.org/community/groups/buddypress-restrict-group-creation/ or get it the WordPress plugin directory.
		
	 
	
	
	
 
		
			
	
	
		
		I installed this one, but couldn’t figure out how to configure. I’ll look at it again. Thanks.
		
	 
	
	
	
 
		
			
	
	
		
		This chart might help:  WP Roles & Capabilities.
		
	 
	
	
	
 
		
			
	
	
		
		Thanks, again! It makes sense now.
		
	 
	
	
	
 
		
			
	
	
		
		This plugin is way out of date!  Please update.
however it does seem to work in wp 3.0.1 and the latest BP as of today. 1.2.5.2 I think?
		
	 
	
	
	
 
		
			
	
	
		
		 @bionicclick what is out of date about it – if it works fine on the latest WP/BP? can you report the bugs to me? -> https://buddypress.org/community/groups/buddypress-restrict-group-creation/
		
	 
	
	
	
 
		
			
	
	
		
		Maybe I’m stupid, but the settings of this plugin doesn’t make sense to me. I only want Super Admin/Administrator to be able to create groups and no subscribers or anyone lower than Super Admin/Administrator.