Re: "Edit with Microsoft Excel" on a Mac

Hi Chris,

The “Edit in Microsoft Excel” feature requires Active X which is only supported in Internet Explorer. In Firefox, you can either edit the file with Excel Web App, or download the file to edit it.

For your reference:
Get started with Office Web Apps in Office 365
http://office.microsoft.com/en-us/web-apps-help/get-started-with-office-web-apps-in-office-365-HA102619009.aspx?CTT=1

Thanks,
Evan Zhang