diff --git a/src/bin/ent/main.rs b/src/bin/ent/main.rs
index 1c9ddaa..1982feb 100644
--- a/src/bin/ent/main.rs
+++ b/src/bin/ent/main.rs
@@ -23,7 +23,11 @@ struct Args {
 #[derive(clap::Subcommand, Debug)]
 enum Commands {
     /// List issues.
-    List,
+    List {
+        /// Filter string, describes issues to include in the list.
+        #[arg(default_value_t = String::from("state=New,Backlog,Blocked,InProgress"))]
+        filter: String,
+    },
 
     /// Create a new issue.
     New { description: Option<String> },
@@ -49,11 +53,14 @@ enum Commands {
 
 fn handle_command(args: &Args, issues_dir: &std::path::Path) -> anyhow::Result<()> {
     match &args.command {
-        Commands::List => {
+        Commands::List { filter } => {
             let issues =
                 entomologist::issues::Issues::new_from_dir(std::path::Path::new(issues_dir))?;
+            let filter = entomologist::parse_filter(filter)?;
             for (uuid, issue) in issues.issues.iter() {
-                println!("{} {} ({:?})", uuid, issue.title(), issue.state);
+                if filter.include_states.contains(&issue.state) {
+                    println!("{} {} ({:?})", uuid, issue.title(), issue.state);
+                }
             }
         }
 
diff --git a/src/issue.rs b/src/issue.rs
index c762c82..6ce8e46 100644
--- a/src/issue.rs
+++ b/src/issue.rs
@@ -5,7 +5,7 @@ use std::str::FromStr;
 #[cfg(feature = "log")]
 use log::debug;
 
-#[derive(Clone, Debug, PartialEq, serde::Deserialize)]
+#[derive(Clone, Debug, Eq, Hash, PartialEq, serde::Deserialize)]
 /// These are the states an issue can be in.
 pub enum State {
     New,
@@ -38,6 +38,8 @@ pub enum IssueError {
     CommentError(#[from] crate::comment::CommentError),
     #[error("Failed to parse issue")]
     IssueParseError,
+    #[error("Failed to parse state")]
+    StateParseError,
     #[error("Failed to run git")]
     GitError(#[from] crate::git::GitError),
     #[error("Failed to run editor")]
@@ -61,7 +63,7 @@ impl FromStr for State {
         } else if s == "wontdo" {
             Ok(State::WontDo)
         } else {
-            Err(IssueError::IssueParseError)
+            Err(IssueError::StateParseError)
         }
     }
 }
@@ -75,7 +77,6 @@ impl fmt::Display for State {
             State::InProgress => "inprogress",
             State::Done => "done",
             State::WontDo => "wontdo",
-            
         };
         write!(f, "{fmt_str}")
     }
diff --git a/src/lib.rs b/src/lib.rs
index e129eff..77a00d9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,40 @@
+use std::str::FromStr;
+
 pub mod comment;
 pub mod git;
 pub mod issue;
 pub mod issues;
+
+#[derive(Debug, thiserror::Error)]
+pub enum ParseFilterError {
+    #[error("Failed to parse filter")]
+    ParseError,
+    #[error(transparent)]
+    IssueParseError(#[from] crate::issue::IssueError),
+}
+
+// FIXME: It's easy to imagine a full dsl for filtering issues, for now
+// i'm starting with obvious easy things.  Chumsky looks appealing but
+// more research is needed.
+#[derive(Debug)]
+pub struct Filter {
+    pub include_states: std::collections::HashSet<crate::issue::State>,
+}
+
+// Parses a filter description matching "state=STATE[,STATE*]"
+pub fn parse_filter(filter_str: &str) -> Result<Filter, ParseFilterError> {
+    let tokens: Vec<&str> = filter_str.split("=").collect();
+    if tokens.len() != 2 {
+        return Err(ParseFilterError::ParseError);
+    }
+    if tokens[0] != "state" {
+        return Err(ParseFilterError::ParseError);
+    }
+
+    let mut include_states = std::collections::HashSet::<crate::issue::State>::new();
+    for s in tokens[1].split(",") {
+        include_states.insert(crate::issue::State::from_str(s)?);
+    }
+
+    Ok(Filter { include_states })
+}