Here are a series of assessment questionnaires and handouts for Generalized Anxiety Disorder:

GAD, 2 question screen - answering "yes" to either of the two screening questions on this sheet suggests it's worth checking for a diagnosis of full Generalized Anxiety Disorder (GAD) - for example by using the GADQ (see below).

GAD, questionnaire (GADQ) - a simple questionnaire for making a full diagnosis of GAD.

GAD, assessment (GADSS) and scoring - the GAD Severity Scale.  Useful, and pays more attention to GAD's associated physical symptoms than the more purely worry-focussed scales that are often used.

GAD, metacognitions (Wells) - GAD assessment scale developed by Wells.  Includes measures of safety behaviours and metacognitions.

GAD, brief measure of worry (BMWS) - a PDF of an interesting worry questionnaire developed by the Australian Black Dog Institute.

GAD, assessment (PSWQ) - the Penn State Worry Questionnaire (PSWQ) is possibly the most widely used measures for GAD.  Here is a copy with some scoring information on the third page. 

GAD, weekly assessment (PSWQ-PW) - you may find an adapted "weekly" version of the PSWQ is easier to use when monitoring therapeutic progress.  Here is the PSWQ-PW, again with some scoring information on the third page of the download. 

GAD, worry record (Borkovec) - Tom Borkovec and colleagues reported that about 85% of worries/fears that a GAD sufferer experienced never happened.  For the 10-15% that did happen, they routinely found that the difficulty was coped with much better than the sufferer feared.  This Worry Record encourages people to check this out for themselves - a good behavioural experiment.

GAD, worry tree and reducing worry tendencies - the Worry Tree is a helpful two slide Powerpoint handout for dealing with immediate worries.  The Reducing Worry Tendencies is similar but looks more at the medium term.  Tom Borkovec's hopes for the value of emotional/interpersonal additional work still needs to be validated before being taken as routinely relevant.

GAD, Powerpoint miniatures (Borkovec) - in the autumn of 2004, I spent a week with Tom at Penn State University in the US.  This 12 slide Powerpoint presentation is a short talk I subsequently gave about the experience and about GAD.