How to find controls in a repeater header or footer

Better solution

You can check item type in ItemCreated event:

protected void rptSummary_ItemCreated(Object sender, RepeaterItemEventArgs e) {
    if (e.Item.ItemType == ListItemType.Footer) {
        e.Item.FindControl(ctrl);
    }
    if (e.Item.ItemType == ListItemType.Header) {
        e.Item.FindControl(ctrl);
    }
}

As noted in the comments, this only works AFTER you've DataBound your repeater.

To find a control in the header:

lblControl = repeater1.Controls[0].Controls[0].FindControl("lblControl");

To find a control in the footer:

lblControl = repeater1.Controls[repeater1.Controls.Count - 1].Controls[0].FindControl("lblControl");

---

With extension methods

public static class RepeaterExtensionMethods
{
    public static Control FindControlInHeader(this Repeater repeater, string controlName)
    {
        return repeater.Controls[0].Controls[0].FindControl(controlName);
    }

    public static Control FindControlInFooter(this Repeater repeater, string controlName)
    {
        return repeater.Controls[repeater.Controls.Count - 1].Controls[0].FindControl(controlName);
    }
}