diff --git a/Types.hs b/Types.hs
index 8e53611..e818c63 100644
--- a/Types.hs
+++ b/Types.hs
@@ -1,4 +1,6 @@
 {-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE ApplicativeDo #-}
+{-# LANGUAGE RecordWildCards #-}
 
 -- | Separated-out main types of the deployment scriptage.
 module Types where
@@ -8,6 +10,7 @@ import qualified Data.Map as M
 import qualified Data.Set as S
 import qualified Data.Yaml as Y
 import Lens.Micro.TH
+import Options.Applicative
 import qualified Text.Mustache as Mu
 import qualified Text.Pandoc.Definition
 
@@ -51,23 +54,63 @@ data SiteState =
 
 makeLenses ''SiteState
 
--- | Make a completely empty `SiteState` for the `Site` monad.
-emptySiteState =
-  SiteState
-    { _pages = M.empty
-    , _redirects = M.empty
-    , _htags = M.empty
-    , _installs = S.empty
-    , _targets = S.empty
-    , _templates = M.empty
-    , _outputDir = "_site"
-    , _assetDir = "assets"
-    , _defaultTemplate = "default.html"
-    , _redirectTemplate = "redirect.html"
-    , _tagTemplate = "tag.html"
-    , _urlBase = "/"
-    , _dumpFinalState = False
-    }
-
 -- | Monad for running the site generator.
 type Site a = StateT SiteState IO a
+
+-- | Parser for commandline options
+siteOptions' :: Parser SiteState
+siteOptions' = do
+  _outputDir <-
+    strOption $
+    long "output" <>
+    short 'd' <>
+    help "Directory to render the site to" <> value "_site" <> showDefault
+  _assetDir <-
+    strOption $
+    long "assets" <>
+    short 'a' <>
+    help "Assets directory to be copied verbatim" <>
+    value "assets" <> showDefault
+  --TODO templates directory!
+  _defaultTemplate <-
+    strOption $
+    long "default-template" <>
+    help "Default template to use for stuff (found in templates directory)" <>
+    value "default.html" <> showDefault
+  _redirectTemplate <-
+    strOption $
+    long "redirect-template" <>
+    help "Template for making redirect pages" <>
+    value "redirect.html" <> showDefault
+  _tagTemplate <-
+    strOption $
+    long "tag-template" <>
+    help "Template for making tag-listing pages" <>
+    value "tag.html" <> showDefault
+  _urlBase <-
+    strOption $
+    long "url-base" <>
+    short 'u' <> help "Base absolute URL" <> value "/" <> showDefault
+  _dumpFinalState <-
+    switch $
+    long "dump-state" <>
+    short 'D' <>
+    help "Print out the complete internal state after the site is built"
+  pure
+    SiteState
+      { _pages = M.empty
+      , _redirects = M.empty
+      , _htags = M.empty
+      , _installs = S.empty
+      , _targets = S.empty
+      , _templates = M.empty
+      , ..
+      }
+
+-- | ParserInfo for commandline options
+siteOptions =
+  info
+    (siteOptions' <**> helper)
+    (fullDesc <>
+     progDesc "Build a R3 Cards-like site" <>
+     header "site - the R3 site builder")
diff --git a/reploy.cabal b/reploy.cabal
index a41412e..1d16ed2 100644
--- a/reploy.cabal
+++ b/reploy.cabal
@@ -19,6 +19,7 @@ executable site
                   , microlens-mtl
                   , microlens-th
                   , mustache
+                  , optparse-applicative
                   , pandoc
                   , pandoc-types
                   , parsec
diff --git a/site.hs b/site.hs
index affb61d..b6f6840 100644
--- a/site.hs
+++ b/site.hs
@@ -36,6 +36,7 @@ import Text.Pandoc.Class (runIOorExplode)
 import Text.Pandoc.Readers.Markdown (readMarkdown)
 import Text.Pandoc.Writers.HTML (writeHtml5String)
 import qualified Text.Parsec.Error
+import qualified Options.Applicative
 
 import FormatOpts
 import Types
@@ -316,8 +317,9 @@ renderTags :: Site ()
 renderTags = use (htags . to M.keys) >>= traverse_ renderTag
 
 -- | Build the whole site.
-main =
-  flip runStateT emptySiteState $ do
+main = do
+  init <- Options.Applicative.execParser siteOptions
+  flip runStateT init $ do
     installAssets
     traverse sourcePages ["external"]
     sourceTags