There has been a change in the APA 6th Edition Style Guide on page 4 in the ‘In-Text Punctuation’ section.
The rule "Use two spaces after punctuation marks at the end of a sentence" has been changed to "Use one space after punctuation marks at the end of a sentence." The two space rule was based on a misreading of section 4.01 in the APA 6th edition manual on page 88 where it states "Exceptions:… Spacing twice after punctuation marks at the end of a sentence aids readers of draft manuscripts." To clarify the meaning of this, CDD Curriculum editors emailed APA manual editors, who informed them that two spaces after punctuation is optional for drafts, and , more importantly, that any paper submitted to instructors is not considered a draft. Therefore, the one-space-after-punctuation rule applies to all written assignments.