diff --git a/microtip.js b/microtip.js
index 07c1226..b45eafb 100644
--- a/microtip.js
+++ b/microtip.js
@@ -14,6 +14,28 @@ function get_tips() {
     return tips_on_this_page
 }
 
+// testcases:
+// pass_blacklist_and_whitelist('whitelist', ['aa', 'bb'], 'aa') == true; // in whitelist
+// pass_blacklist_and_whitelist('whitelist', ['aa', 'bb'], 'xx') == false; // not in whitelist
+// pass_blacklist_and_whitelist('blacklist', ['aa', 'bb'], 'aa') == false; // in blacklist
+// pass_blacklist_and_whitelist('blacklist', ['aa', 'bb'], 'cc') == true; // not in blacklist
+function pass_blacklist_and_whitelist(setting, domains, this_domain) {
+    // setting: either 'blacklist' or 'whitelist'
+    // domains: list of strings (domain's that make up the white/blacklist)
+    // this_domain: the domain that this page is on
+    // returns: true or false, depending on whether this_domain passes or fails the black/whitelist
+
+    for(var i = 0; i < domains.length; i++){
+        var domain = domains[i];
+        if(domain == this_domain) {
+            return setting == 'whitelist';
+        }
+    };
+
+    return setting == 'blacklist';
+}
+
+
 chrome.storage.sync.get({
     when_to_send: null,
     blacklist_or_whitelist: null,
@@ -25,24 +47,37 @@ chrome.storage.sync.get({
         return // No tips found
     }
 
+    var pblwl = true;
+    if(items.blacklist_or_whitelist != 'none') {
+        // determine if this page's domain jives with the users black/whitelists.
+        var pblwl = pass_blacklist_and_whitelist(
+            items.blacklist_or_whitelist, items.domain_list, window.location.host
+        )
+    }
+
+    if(!pblwl) {
+        console.log("Autotip canceled because of", items.blacklist_or_whitelist);
+        console.log(items.domain_list, window.location.host);
+    }
+
     console.log("Autotip extension found " + tips.length + " microtip meta tags on this page");
     chrome.runtime.sendMessage({found_tips: tips});
 
-    if(items.when_to_send == '5mins') {
-        var five_minute_counter_start = new Date()
+    if(pblwl && items.when_to_send == '5mins') {
+        var five_minute_counter_start = new Date();
         intervalID = setInterval(function() {
-            // update popup status every 1 second. After 5 minutes, make the tip
+            // update popup status every 1 second. After 5 minutes (or whatever the setting is), make the tip
             var seconds_to_go = Math.floor(items.interval_seconds - ((new Date() - five_minute_counter_start) / 1000));
             if(seconds_to_go <= 0) {
                 chrome.runtime.sendMessage({tips: tips, perform_tip: 'auto'});
                 console.log('5 minutes past, tip made');
                 clearInterval(intervalID);
             } else {
-                var msg = "Sending tip in " + seconds_to_go + " Seconds"
+                var msg = "Sending tip in " + seconds_to_go + " Seconds";
                 chrome.runtime.sendMessage({popup_timer: msg});
             }
         }, 1000);
-    } else if(items.when_to_send == 'immediately') {
+    } else if(pblwl && items.when_to_send == 'immediately') {
         // go ahead and make the tip automatically.
         chrome.runtime.sendMessage({tips: tips, perform_tip: 'auto'});
     }