The three most important themes in "Number the Stars" are the difficulties encountered in growing up, the physical and mental voyages we take throughout life, and the reality of war.  I believe the central theme is growing up and Annemarie Johansen's personal experience doing just that during the challenging times of World War II.  Annemarie is often compared with the very innocent and childlike Kirsti.  But, Annemarie is forced to accept many adult responsibilities like the character Peter Neilsen who has "taken his place in the world of adults." 

The journey theme is covered in the physical trip the Jews must make from Copenhagen to Gilleleje and finally to Sweden.  Mentally Annemarie makes a voyage of discovery as she comes to grips with who she is as a person.

Finally, the reality of war is so terrible and strange that Annemarie can't always believe it is real.  She turns her own life into fiction and is then able to deal with her fears and deliver the important package to her uncle.  But, in the end she also realizes that heroes don't always survive like the death of her hero, Peter Neilsen.