THC Science

If you see a threat of harm (including self-harm):

Many threats are empty, but most Wikipedians do not have the training to make such evaluations.
If you are in immediate danger, call your local emergency services.

Immediately email emergencywikimedia.org with details of the threat.

This address is only for true emergencies and is monitored around the clock. If you have an issue that is not an emergency, please see Wikipedia:Contact us for a more appropriate venue.
You can also use Special:EmailUser/Emergency if you have an account with email enabled.
Include the name of the page where the threat was made, or a diff.
Avoid emailing other addresses or telephoning the Wikimedia Foundation office, as it creates confusion.
Staff will typically acknowledge your email immediately.
Staff will take appropriate action, such as tracing locations and contacting authorities.

In addition to emailing the Wikimedia Foundation as above, notify Wikipedia administrators privately.

Even an administrator discovering a threat should notify other administrators.
Use email, IRC, or other low-visibility methods. Avoid high-traffic noticeboards when reporting.
If in doubt, join #wikipedia-en-revdel ^connect or failing that, in true emergencies there is almost always a steward on #wikimedia-stewards ^connect. If you don't have an IRC client, click the green ^connect button to launch web-based IRC.
Also request oversight, as such posts often contain personal information requiring suppression.

Advice for administrators

Threats of suicide or self-harm require discretion on the questions of blocking or removal of posts.
Threats of violence against others should be met with blocking (generally including removal of talk page access) and possibly blocking email as well. Such threats should be removed; consider also deleting the problematic revision from public view.
If in doubt, email the office at emergencywikimedia.org.