How do I prove that my new construction home stucco exterior surface was incorrectly painted? I have white effloescence showing in multiple places all over my home. It was painted approximately 1 year ago and it showed up about 3 months ago. Looking for any help.

If it is truly efflorescence it is likely the stucco and not the paint at fault. Do you know what type or brand paint was used?

efflorescence indicates moisture migrating outward through the stucco, for instance if the house was painted before the stucco became fully cured. Otherwise, there may be a moisture migration issue separate from the painting issue. Definietely check which paint was applied to ensure it is compatible with the stucco, needs to be applied over a sealer/ primer coat, and how soon after stucco cure it may be used. See Mr. Fowler's article at http://www.stuccoguru.com/resources/article.cfm?articleID=C-02500&resourceID=2 for a summary, or check wikipedia's efflorescence article.