**June 2012 **
Google Recommends Eclipse Helios, Eclipse Classic or Eclipse RCP. For details, read the below post.
URL: http://developer.android.com/sdk/eclipse-adt.html
Look under ADT 18.0.0 (April 2012).
Eclipse Helios (Version 3.6.2) or higher is required for ADT 18.0.0.
Look under Installing the ADT Plugin.
If you need to install or update Eclipse, you can download it from http://www.eclipse.org/downloads/. The "Eclipse Classic" version is recommended. Otherwise, a Java or RCP version of Eclipse is recommended.
April 2014 Updated
Eclipse Indigo (Version 3.7.2) or higher is required. I'll suggest you to use Eclipse Kepler.
ADT 22.6.0 (March 2014)