C# passing data to another project

Question

I want to pass the UserID from my project to another project exe. I call second project with these codes.

using System.Diagnostics;
private void MenuItemClickHandler(object sender, EventArgs e)
{
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.UseShellExecute = false;
startInfo.FileName = @"\\server1\Lawyer\Lawyer.exe";
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
startInfo.Arguments = CurrentUser.UserID.ToString();
Process.Start(startInfo);
}

How can I pass the UserID of my project to second project that I called (Lawyer)? Thanks so much