I was working on an application migration recently, and wanted to see how many users/computers were in each application Active Directory (AD) group in a specified Organisational Unit (OU).  I wrote a PowerShell script to find the membership count of all AD Groups in an OU:

$Groups = Get-ADGroup -Properties * -Filter * -SearchBase "OU=Applications,DC=alkane,DC=co,DC=uk" 
Foreach($group In $groups)
{
    $groupname = $group.Name 
    $groupdescription = $group.Description
    $groupdn = $group.DistinguishedName
    $groupcount = $group.member.count
}

This post provides an example of how to count members of an AD Group and write to a CSV.

This script finds all AD groups beginning with ‘MSI – ‘ or ‘App-V – ‘ and returns the number of members it contains.  Note that it doesn’t recurse nested groups!  It then outputs the results to a CSV file.

$csvPath = "C:\Alkane\AlkaneGroups.csv"

"Group,Count" | Out-File -filepath $csvPath -Append -encoding ASCII

$groups = Get-ADGroup -filter {(name -like "MSI - *") -or (name -like "App-V - *")}
foreach($group in $groups){
	$countUser = (Get-ADGroup $group -Properties *).member.count
	Write-Host "The group $($group.Name) has $countUser user(s)."
	"""$($group.Name)"",$countUser" | Out-File -filepath $csvPath -Append -encoding ASCII
}