Get the first day of the week. ex. DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Monday); DateTime dt = DateTime.Now.StartOfWeek(DayOfWeek.Sunday); Credit to http://stackoverflow.com/a/38064/1467924

StartOfWeek.cs

public static class DateTimeExtensions
{
    public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
    {
        int diff = dt.DayOfWeek - startOfWeek;
        if (diff < 0)
        {
            diff += 7;
        }

        return dt.AddDays(-1 * diff).Date;
    }
}