My friend and I are visiting Amsterdam next month. She is attending a conference and so we only have a narrow window of time to see the Anne Frank museum. The web-site says that the times are already sold out. Does anyone know if you can buy tickets for the shorter line while in Amsterdam? Would it be better to show up an hour before the museum opens and just stand in line? We are trying to maximize our time there.

I honestly don't know, but if you're interested in the period, you could try the Resistance Museum as an alternative:

http://www.verzetsmuseum.org/museum/en/museum

We went to Amsterdam last year May 21-25 and we did not buy our tickets on-line for the Ann Frank museum thinking we would do so when we got there. Our hotel's website said they had a computer and printer just for the purpose of being able to buy/print your museum tickets.

Unfortunately, like you we found all of the time slots already sold out when we went to purchase tickets. So we went without them, showing up first thing in the a.m. about 20 minutes before the museum opened. There were about a dozen folks in line when we arrived. The museum opened promptly, the line moved quickly and we were inside and looking within about 15 minutes after opening. When we came out the admissions line to buy tickets stretched along the side of the building and around the block.

It is well-worth waiting for, but our approach was we'd go 30 minutes early the first day and check out the line and if need be an hour the next. We were told by TI that the wait could easily be 2 hours or more in the afternoon.

They don't put all the tickets for online sales. So there's always a chance of getting in without pre-booking, but depending on the time of day or year, you may have to wait in line.
http://prev.annefrank.org/content.asp?PID=836&LID=2#40

The thing about the Anne Frank House is that even
if the line is long it does move quickly. We
were around the corner and halfway past the church
the last time we were there yet we were inside within half an hour at most.

I was happy to see TX4X's response about showing up early because that's so workable so matter what.

I also think that sometimes they open up slots online. I was being told "sold out" online for a few weeks and then suddenly some days opened up. So what the heck--keep checking and you always have the show-up-early plan.

Our first time, because I just didn't want to commit to a time, we followed the "show up late in the day" advice. Well we DID get in, but the line was so long and I swear it moved at a snail's pace.

The next time (with three other family members), I made sure we committed to a time slot online.

Thanks everyone! I will keep checking the web-site and if that doesn't work, just show up about 8:30 am and wait in line.

I'm sorry. I can't help it. Every time I see the title of the post I want to say NO SHE DID NOT. I know , sorry. Really.

Just in case you haven't come across this Ann Frank House website:

http://www.annefrank.org/en/Subsites/Home/

Your plan is a good one. We were recently there w/o tickets. Arrived 30 minutes before they opened and we were about the fifth in line. Within 15 minutes there were tour groups all over the place so don't be late - it is a great visit.

"Anne Frank sold out" - yes, and nobody knows who did it, who is the traitor!