No size tag - please check measurements!  
I think its girls Size 8 or 10 
Waist is 14" across but can be pulled tighter with waistband tie
Length is 27.5"
One small faint stain on front - pictured.
Matilda Jane Girls Citronella Dress Size 8 or 10 Floral Orange Blue Long Sleeve
Fun Summer Spring Dress. 
Thanks for looking!