diff --git a/static/account_register.js b/static/account_register.js
index e6f780a..8284135 100644
--- a/static/account_register.js
+++ b/static/account_register.js
@@ -1,5 +1,6 @@
 // Import all the objects we want to use from ReactBootstrap
 
+var Alert = ReactBootstrap.Alert;
 var Modal = ReactBootstrap.Modal;
 var Pagination = ReactBootstrap.Pagination;
 
@@ -127,12 +128,16 @@ const AmountInput = React.createClass({
 		var symbol = "?";
 		if (this.props.security)
 			symbol = this.props.security.Symbol;
+		var bsStyle = "";
+		if (this.props.bsStyle)
+			bsStyle = this.props.bsStyle;
 
 		return (
 			<Input type="text"
 				value={this.state.Amount}
 				onChange={this.onChange}
 				addonBefore={symbol}
+				bsStyle={bsStyle}
 				ref="amount"/>
 		);
 	}
@@ -142,7 +147,10 @@ const AddEditTransactionModal = React.createClass({
 	_getInitialState: function(props) {
 		// Ensure we can edit this without screwing up other copies of it
 		var t = props.transaction.deepCopy();
-		return {transaction: t};
+		return {
+			errorAlert: [],
+			transaction: t
+		};
 	},
 	getInitialState: function() {
 		 return this._getInitialState(this.props);
@@ -232,6 +240,24 @@ const AddEditTransactionModal = React.createClass({
 		});
 	},
 	handleSubmit: function() {
+		var errorString = ""
+		var imbalancedSecurityList = this.state.transaction.imbalancedSplitSecurities(this.props.account_map);
+		if (imbalancedSecurityList.length > 0)
+			errorString = "Transaction must balance"
+		for (var i = 0; i < this.state.transaction.Splits.length; i++) {
+			var s = this.state.transaction.Splits[i];
+			if (!(s.AccountId in this.props.account_map)) {
+				errorString = "All accounts must be valid"
+			}
+		}
+
+		if (errorString.length > 0) {
+			this.setState({
+				errorAlert: (<Alert className='saving-transaction-alert' bsStyle='danger'><strong>Error Saving Transaction:</strong> {errorString}</Alert>)
+			});
+			return;
+		}
+
 		if (this.props.onSubmit != null)
 			this.props.onSubmit(this.state.transaction);
 	},
@@ -250,13 +276,25 @@ const AddEditTransactionModal = React.createClass({
 		   );
 		}
 
+		var imbalancedSecurityList = this.state.transaction.imbalancedSplitSecurities(this.props.account_map);
+		var imbalancedSecurityMap = {};
+		for (i = 0; i < imbalancedSecurityList.length; i++)
+			imbalancedSecurityMap[imbalancedSecurityList[i]] = i;
+
 		splits = [];
 		for (var i = 0; i < this.state.transaction.Splits.length; i++) {
 			var self = this;
 			var s = this.state.transaction.Splits[i];
 			var security = null;
-			if (this.props.account_map[s.AccountId])
+			var amountValidation = "";
+			var accountValidation = "";
+			if (s.AccountId in this.props.account_map) {
 				security = this.props.security_map[this.props.account_map[s.AccountId].SecurityId];
+				if (security.SecurityId in imbalancedSecurityMap)
+					amountValidation = "error";
+			} else {
+				accountValidation = "has-error";
+			}
 
 			// Define all closures for calling split-updating functions
 			var deleteSplitFn = (function() {
@@ -307,12 +345,14 @@ const AddEditTransactionModal = React.createClass({
 					value={s.AccountId}
 					includeRoot={false}
 					onSelect={updateAccountFn}
-					ref={"account-"+i} /></Col>
+					ref={"account-"+i}
+					className={accountValidation}/></Col>
 				<Col xs={2}><AmountInput type="text"
 					value={s.Amount}
 					security={security}
 					onChange={updateAmountFn}
-					ref={"amount-"+i} /></Col>
+					ref={"amount-"+i}
+					bsStyle={amountValidation}/></Col>
 				{deleteSplitButton}
 				</Row>
 			));
@@ -367,6 +407,7 @@ const AddEditTransactionModal = React.createClass({
 								bsStyle="success">
 								<Glyphicon glyph='plus-sign' /></Button></Col>
 					</Row>
+					<Row>{this.state.errorAlert}</Row>
 					</Grid>
 				</form>
 				</Modal.Body>
diff --git a/static/accounts.js b/static/accounts.js
index 8cf5022..2f8fc06 100644
--- a/static/accounts.js
+++ b/static/accounts.js
@@ -31,6 +31,9 @@ const AccountCombobox = React.createClass({
 	},
 	render: function() {
 		var accounts = getAccountDisplayList(this.props.accounts, this.props.includeRoot, this.props.rootName);
+		var className = "";
+		if (this.props.className)
+			className = this.props.className;
 		return (
 			<Combobox
 				data={accounts}
@@ -38,7 +41,8 @@ const AccountCombobox = React.createClass({
 				textField='Name'
 				value={this.props.value}
 				onSelect={this.handleAccountChange}
-				ref="account" />
+				ref="account"
+				className={className} />
 	   );
 	}
 });
diff --git a/static/models.js b/static/models.js
index 7a47434..38dfa88 100644
--- a/static/models.js
+++ b/static/models.js
@@ -323,6 +323,33 @@ Transaction.prototype.deepCopy = function() {
 	return t;
 }
 
+Transaction.prototype.imbalancedSplitSecurities = function(account_map) {
+	// Return a list of SecurityIDs for those securities that aren't balanced
+	// in this transaction's splits. If a split's AccountId is invalid, that
+	// split is ignored, so those must be checked elsewhere
+	var splitBalances = {};
+	const emptySplit = new Split();
+	for (var i = 0; i < this.Splits.length; i++) {
+		split = this.Splits[i];
+		if (split.AccountId == emptySplit.AccountId) {
+			continue;
+		}
+		var securityId = account_map[split.AccountId].SecurityId;
+		if (securityId in splitBalances) {
+			splitBalances[securityId] = split.Amount.plus(splitBalances[securityId]);
+		} else {
+			splitBalances[securityId] = split.Amount.plus(0);
+		}
+	}
+	var imbalancedIDs = [];
+	for (var id in splitBalances) {
+		if (!splitBalances[id].eq(0)) {
+			imbalancedIDs.push(id);
+		}
+	}
+	return imbalancedIDs;
+}
+
 function Error() {
 	this.ErrorId = -1;
 	this.ErrorString = "";
diff --git a/static/stylesheet.css b/static/stylesheet.css
index 6f3e0d8..e6a8e77 100644
--- a/static/stylesheet.css
+++ b/static/stylesheet.css
@@ -115,3 +115,22 @@ div.accounttree-root div {
 .skinny-pagination {
 	margin: 0px;
 }
+
+/* Make Combobox support .has-error class */
+.has-error.rw-widget {
+	border-color: #843534;
+}
+.has-error.rw-widget.rw-state-focus {
+	border-color: #843534;
+	box-shadow: 0px 1px 1px rgba(0, 0, 0, 0.075) inset, 0px 0px 6px #CE8483;
+}
+.has-error.rw-widget > .rw-select {
+	border-left: 1px solid #843534;
+	color: #A94442;
+	background-color: #F2DEDE;
+}
+
+/* Fix Alert Spacing inside */
+.alert.saving-transaction-alert {
+	margin: 20px 0 0 0;
+}