Assign Category via Guest Entry Form Is is possible to assign a category via a frontend Guest Entry form.

I tried 

&lt;input type="hidden" name="fieldHandle" value="SomeExistingCategorySlug"&gt;


But that did not work.
Simply put, a Categories field is an array containing category ids, and your form needs to send it that way:

&lt;input type="hidden" name="fields[fieldHandle][]" value="100"&gt;


Adding brackets to your field-handle submits the value as an array, and 100 is the id of the category.