1diff --git a/src/RawFormulas/Date.ts b/src/RawFormulas/Date.ts
  2index 6369a7e..83a57a9 100644
  3--- a/src/RawFormulas/Date.ts
  4+++ b/src/RawFormulas/Date.ts
  5@@ -8,6 +8,7 @@ import {
  6 } from "./Utils";
  7 import {
  8   NUM_ERROR,
  9+  VALUE_ERROR,
 10   CellError
 11 } from "../Errors";
 12 import {
 13@@ -40,30 +41,31 @@ var DATE = function (...values) {
 14 /**
 15  * Converts a provided date string in a known format to a date value.
 16  * @param values[0] date_string - The string representing the date. Understood formats include any date format which is
 17- * normally autoconverted when entered, without quotation marks, directly into a cell. Understood formats may depend on
 18- * region and language settings. Examples include: "1/23/2012", "1/23/2012 8:10:30", "2012/1/23", "2012-1-23"
 19- * @returns {number}
 20+ * normally auto-converted when entered, without quotation marks, directly into a cell. Understood formats may depend on
 21+ * region and language settings. Examples include: "1/23/2012", "2012/1/23", "2012-1-23", "1-23-2012", "1/23/2012 8PM",
 22+ * "1/23/2012 8:10:30", "1/23/2012 8:10", "1/23/2012 8:10:300000000"
 23+ * @returns {number} of days since 1900/1/1
 24  * @constructor
 25  */
 26 var DATEVALUE = function (...values) : number {
 27   ArgsChecker.checkLength(values, 1);
 28   var dateString = TypeCaster.firstValueAsString(values[0]);
 29-  var dateNumber;
 30+  var m;
 31   if (RegExUtil.matchDateStringYearMonthDaySlash(dateString)) { // Check "2012/1/23"
 32-    dateNumber = new ExcelDate(moment(dateString, "Y/M/D")).toNumber();
 33+    m = moment(dateString, "Y/M/D");
 34   } else if (RegExUtil.matchDateStringYearMonthDayHyphen(dateString)) { // Check "2012-1-23"
 35-    dateNumber = new ExcelDate(moment(dateString, "Y-M-D")).toNumber();
 36+    m = moment(dateString, "Y-M-D");
 37   } else if (RegExUtil.matchDateStringMonthDayYearSlash(dateString)) { // Check "1/23/2012"
 38-    dateNumber = new ExcelDate(moment(dateString, "M/D/Y")).toNumber();
 39-  }
 40-  if (dateNumber === undefined) {
 41-    // TODO: Throw error that we couldn't parse the dateString.
 42+    m = moment(dateString, "M/D/Y");
 43+  } else if (RegExUtil.matchDateStringMonthDayYearHyphen(dateString)) { // Check "1-23-2012"
 44+    m = moment(dateString, "M-D-Y");
 45+  } else if (RegExUtil.matchDateStringMonthDayYearTimeStampAll(dateString)) { // Check "1/23/2012 8:10", "1-23-2012 8:10", "1/23/2012 8PM", etc.
 46+
 47   }
 48-  if (dateNumber < 0) {
 49-    throw new CellError(NUM_ERROR, "DATEVALUE evaluates to an out of range value " + dateNumber
 50-      + ". It should be greater than or equal to 0.");
 51+  if (m === undefined || !m.isValid()) {
 52+    throw new CellError(VALUE_ERROR, "DATEVALUE parameter '" + dateString + "' cannot be parsed to date/time.");
 53   }
 54-  return dateNumber;
 55+  return new ExcelDate(m).toNumber();
 56 };
 57 
 58 
 59diff --git a/src/RawFormulas/Utils.ts b/src/RawFormulas/Utils.ts
 60index b98d7eb..f206f35 100644
 61--- a/src/RawFormulas/Utils.ts
 62+++ b/src/RawFormulas/Utils.ts
 63@@ -371,6 +371,8 @@ class RegExUtil {
 64   private static DAY_MONTH_YEAR_SLASH_REGEX = /^\s*([1-9]|[0-2][0-9]|3[0-1])\/([1-9]|0[1-9]|1[0-2])\/([1-9][0-9][0-9][0-9])\s*$/;
 65   private static YEAR_MONTH_DAY_SLASH_REGEX = /^\s*([1-9][0-9][0-9][0-9])\/([1-9]|0[1-9]|1[0-2])\/([1-9]|[0-2][0-9]|3[0-1])\s*$/;
 66   private static YEAR_MONTH_DAY_HYPHEN_REGEX = /^\s*([1-9][0-9][0-9][0-9])-([1-9]|0[1-9]|1[0-2])-([1-9]|[0-2][0-9]|3[0-1])\s*$/;
 67+  private static MONTH_DAY_YEAR_HYPHEN_REGEX = /^\s*([1-9]|0[1-9]|1[0-2])-([1-9]|[0-2][0-9]|3[0-1])-([1-9][0-9][0-9][0-9])\s*$/;
 68+  private static MONTH_DAY_YEAR_TIMESTAMP_REGEX = /^.*$/;
 69 
 70   /**
 71    * Match dates in the form "mm/dd/yyyy" or "m/d/yyyy".
 72@@ -408,6 +410,23 @@ class RegExUtil {
 73     return dateString.match(this.YEAR_MONTH_DAY_HYPHEN_REGEX);
 74   }
 75 
 76+  /**
 77+   * Match dates in the form "mm-dd-yyyy" or "m-d-yyyy".
 78+   * @param dateString to match
 79+   * @returns {RegExpMatchArray} matches or null
 80+   */
 81+  static matchDateStringMonthDayYearHyphen(dateString : string) : RegExpMatchArray | null {
 82+    return dateString.match(this.MONTH_DAY_YEAR_HYPHEN_REGEX);
 83+  }
 84+
 85+  /**
 86+   * Matches dates in the form "mm-dd-yyyy XX:XX:XX:XXX"
 87+   * @param dateString
 88+   * @returns {RegExpMatchArray}
 89+   */
 90+  static matchDateStringMonthDayYearTimeStampAll(dateString: string) : RegExpMatchArray | null {
 91+    return dateString.match(this.MONTH_DAY_YEAR_TIMESTAMP_REGEX);
 92+  };
 93 }
 94 
 95 export {
 96diff --git a/tests/FormulasTest.ts b/tests/FormulasTest.ts
 97index a0586a8..7a81e27 100644
 98--- a/tests/FormulasTest.ts
 99+++ b/tests/FormulasTest.ts
100@@ -812,6 +812,22 @@ assertEquals(DATEVALUE("1992-1-24"), 33627);
101 assertEquals(DATEVALUE("1992-12-21"), 33959);
102 assertEquals(DATEVALUE("1992-01-31"), 33634);
103 assertEquals(DATEVALUE("1992-1-13"), 33616);
104+// m-d-yyyy
105+assertEquals(DATEVALUE("6-24-1992"), 33779);
106+assertEquals(DATEVALUE("06-24-1992"), 33779);
107+assertEquals(DATEVALUE("1-01-1999"), 36161);
108+assertEquals(DATEVALUE("1-01-2222"), 117610);
109+assertEquals(DATEVALUE("9-02-1902"), 976);
110+assertEquals(DATEVALUE("9-2-1902"), 976);
111+assertEquals(DATEVALUE("11-3-4243"), 856071);
112+assertEquals(DATEVALUE("  04-19-1992  "), 33713);
113+assertEquals(DATEVALUE("5-20-1992"), 33744);
114+assertEquals(DATEVALUE("6-21-1992"), 33776);
115+assertEquals(DATEVALUE("9-29-1992"), 33876);
116+assertEquals(DATEVALUE("1-24-1992"), 33627);
117+assertEquals(DATEVALUE("12-21-1992"), 33959);
118+assertEquals(DATEVALUE("01-31-1992"), 33634);
119+assertEquals(DATEVALUE("1-13-1992"), 33616);
120 
121 
122