Comma Code (Python) (Automate The Boring Stuff)
Don't surround sub-predicates or predicates with parens when that isn't needed
Use logical and rather than binary &amp;
Use join rather than a for-and-concatenate
Factor out common sub-predicates for your list emptiness checks into an outer if
Don't else-after-break
No need to continue
Gather your input in a separate function
Do not leave the input prompt blank

Suggested:
def and_add(alist):
    if len(alist) &gt; 1:
        print(', '.join(alist[:-1]), 'and', alist[-1])
    elif len(alist) == 1:
        print(alist[0])
    else:
        print('')

def get_input():
    while True:
        item = input('Enter an item or nothing: ')
        if not item:
            return
        yield item

and_add(list(get_input()))