diff --git a/src/BuildConfig.cc b/src/BuildConfig.cc
index 5ceffcd48..70ff2fbed 100644
--- a/src/BuildConfig.cc
+++ b/src/BuildConfig.cc
@@ -64,6 +64,11 @@ operator<<(std::ostream& os, VarType type) {
 
 BuildConfig::BuildConfig(const std::string& packageName, const bool isDebug)
     : packageName{ packageName }, isDebug{ isDebug } {
+  if (packageName.starts_with("lib")) {
+    libName = fmt::format("{}.a", packageName);
+  } else {
+    libName = fmt::format("lib{}.a", packageName);
+  }
   const fs::path projectBasePath = getProjectBasePath();
   if (isDebug) {
     outBasePath = projectBasePath / "poac-out" / "debug";
@@ -486,12 +491,21 @@ BuildConfig::defineCompileTarget(
 }
 
 void
-BuildConfig::defineLinkTarget(
-    const std::string& binTarget, const std::unordered_set<std::string>& deps
+BuildConfig::defineOutputTarget(
+    const std::unordered_set<std::string>& buildObjTargets,
+    const std::string& targetInputPath,
+    const std::vector<std::string>& commands,
+    const std::string& targetOutputPath
 ) {
-  std::vector<std::string> commands;
-  commands.emplace_back("$(CXX) $(CXXFLAGS) $^ $(LIBS) -o $@");
-  defineTarget(binTarget, commands, deps);
+  // Project binary target.
+  std::unordered_set<std::string> projTargetDeps = { targetInputPath };
+  collectBinDepObjs(
+      projTargetDeps, "",
+      targets.at(targetInputPath).remDeps,  // we don't need sourceFile
+      buildObjTargets
+  );
+
+  defineTarget(targetOutputPath, commands, projTargetDeps);
 }
 
 // Map a path to header file to the corresponding object file.
@@ -760,7 +774,8 @@ BuildConfig::processUnittestSrc(
   );
 
   // Test binary target.
-  defineLinkTarget(testTarget, testTargetDeps);
+  const std::vector<std::string> commands = { LINK_BIN_COMMAND };
+  defineTarget(testTarget, commands, testTargetDeps);
 
   testTargets.insert(testTarget);
   if (mtx) {
@@ -791,6 +806,9 @@ BuildConfig::configureBuild() {
   const auto isMainSource = [](const fs::path& file) {
     return file.filename().stem() == "main";
   };
+  const auto isLibSource = [](const fs::path& file) {
+    return file.filename().stem() == "lib";
+  };
   fs::path mainSource;
   for (const auto& entry : fs::directory_iterator(srcDir)) {
     const fs::path& path = entry.path();
@@ -800,15 +818,33 @@ BuildConfig::configureBuild() {
     if (!isMainSource(path)) {
       continue;
     }
-    if (mainSource.empty()) {
-      mainSource = path;
-    } else {
+    if (!mainSource.empty()) {
       throw PoacError("multiple main sources were found");
     }
+    mainSource = path;
+    hasBinaryTarget = true;
   }
 
-  if (mainSource.empty()) {
-    throw PoacError(fmt::format("src/main{} was not found", SOURCE_FILE_EXTS));
+  fs::path libSource;
+  for (const auto& entry : fs::directory_iterator(srcDir)) {
+    const fs::path& path = entry.path();
+    if (!SOURCE_FILE_EXTS.contains(path.extension())) {
+      continue;
+    }
+    if (!isLibSource(path)) {
+      continue;
+    }
+    if (!libSource.empty()) {
+      throw PoacError("multiple lib sources were found");
+    }
+    libSource = path;
+    hasLibraryTarget = true;
+  }
+
+  if (!hasBinaryTarget && !hasLibraryTarget) {
+    throw PoacError(
+        fmt::format("src/(main|lib){} was not found", SOURCE_FILE_EXTS)
+    );
   }
 
   if (!fs::exists(outBasePath)) {
@@ -817,8 +853,16 @@ BuildConfig::configureBuild() {
 
   setVariables();
 
+  std::unordered_set<std::string> all = {};
+  if (hasBinaryTarget) {
+    all.insert(packageName);
+  }
+  if (hasLibraryTarget) {
+    all.insert(libName);
+  }
+
   // Build rules
-  setAll({ packageName });
+  setAll(all);
   addPhony("all");
 
   std::vector<fs::path> sourceFilePaths = listSourceFilePaths(srcDir);
@@ -832,7 +876,16 @@ BuildConfig::configureBuild() {
           "Move it directly to 'src/' if intended as such.",
           sourceFilePath.string()
       );
+    } else if (sourceFilePath != libSource && isLibSource(sourceFilePath)) {
+      logger::warn(
+          "source file `{}` is named `lib` but is not located directly in the "
+          "`src/` directory. "
+          "This file will not be treated as a hasLibraryTarget. "
+          "Move it directly to 'src/' if intended as such.",
+          sourceFilePath.string()
+      );
     }
+
     srcs += ' ' + sourceFilePath.string();
   }
 
@@ -842,16 +895,20 @@ BuildConfig::configureBuild() {
   const std::unordered_set<std::string> buildObjTargets =
       processSources(sourceFilePaths);
 
-  // Project binary target.
-  const std::string mainObjTarget = buildOutPath / "main.o";
-  std::unordered_set<std::string> projTargetDeps = { mainObjTarget };
-  collectBinDepObjs(
-      projTargetDeps, "",
-      targets.at(mainObjTarget).remDeps,  // we don't need sourceFile
-      buildObjTargets
-  );
+  if (hasBinaryTarget) {
+    const std::vector<std::string> commands = { LINK_BIN_COMMAND };
+    defineOutputTarget(
+        buildObjTargets, buildOutPath / "main.o", commands,
+        outBasePath / packageName
+    );
+  }
 
-  defineLinkTarget(outBasePath / packageName, projTargetDeps);
+  if (hasLibraryTarget) {
+    const std::vector<std::string> commands = { ARCHIVE_LIB_COMMAND };
+    defineOutputTarget(
+        buildObjTargets, buildOutPath / "lib.o", commands, outBasePath / libName
+    );
+  }
 
   // Test Pass
   std::unordered_set<std::string> testTargets;
diff --git a/src/BuildConfig.hpp b/src/BuildConfig.hpp
index e7e14389d..7b2944b2a 100644
--- a/src/BuildConfig.hpp
+++ b/src/BuildConfig.hpp
@@ -22,6 +22,10 @@ inline const std::unordered_set<std::string> HEADER_FILE_EXTS{
 };
 // clang-format on
 
+inline const std::string LINK_BIN_COMMAND =
+    "$(CXX) $(CXXFLAGS) $^ $(LIBS) -o $@";
+inline const std::string ARCHIVE_LIB_COMMAND = "ar rcs $@ $^";
+
 enum class VarType : uint8_t {
   Recursive,  // =
   Simple,     // :=
@@ -47,10 +51,16 @@ struct BuildConfig {
 
 private:
   std::string packageName;
+  std::string libName;
   fs::path buildOutPath;
   fs::path unittestOutPath;
   bool isDebug;
 
+  // if we are building an binary
+  bool hasBinaryTarget{ false };
+  // if we are building a hasLibraryTarget
+  bool hasLibraryTarget{ false };
+
   std::unordered_map<std::string, Variable> variables;
   std::unordered_map<std::string, std::vector<std::string>> varDeps;
   std::unordered_map<std::string, Target> targets;
@@ -67,6 +77,16 @@ struct BuildConfig {
 public:
   explicit BuildConfig(const std::string& packageName, bool isDebug = true);
 
+  bool hasBinTarget() const {
+    return hasBinaryTarget;
+  }
+  bool hasLibTarget() const {
+    return hasLibraryTarget;
+  }
+  const std::string& getLibName() const {
+    return this->libName;
+  }
+
   void defineVar(
       const std::string& name, const Variable& value,
       const std::unordered_set<std::string>& dependsOn = {}
@@ -77,12 +97,14 @@ struct BuildConfig {
       varDeps[dep].push_back(name);
     }
   }
+
   void defineSimpleVar(
       const std::string& name, const std::string& value,
       const std::unordered_set<std::string>& dependsOn = {}
   ) {
     defineVar(name, { .value = value, .type = VarType::Simple }, dependsOn);
   }
+
   void defineCondVar(
       const std::string& name, const std::string& value,
       const std::unordered_set<std::string>& dependsOn = {}
@@ -142,8 +164,12 @@ struct BuildConfig {
       const std::string& objTarget, const std::string& sourceFile,
       const std::unordered_set<std::string>& remDeps, bool isTest = false
   );
-  void defineLinkTarget(
-      const std::string& binTarget, const std::unordered_set<std::string>& deps
+
+  void defineOutputTarget(
+      const std::unordered_set<std::string>& buildObjTargets,
+      const std::string& targetInputPath,
+      const std::vector<std::string>& commands,
+      const std::string& targetOutputPath
   );
 
   void collectBinDepObjs(  // NOLINT(misc-no-recursion)
diff --git a/src/Cmd/Build.cc b/src/Cmd/Build.cc
index 74d1b4ba3..b3126842f 100644
--- a/src/Cmd/Build.cc
+++ b/src/Cmd/Build.cc
@@ -33,29 +33,45 @@ const Subcmd BUILD_CMD =
         .setMainFn(buildMain);
 
 int
-buildImpl(std::string& outDir, const bool isDebug) {
-  const auto start = std::chrono::steady_clock::now();
-
-  const BuildConfig config = emitMakefile(isDebug, /*includeDevDeps=*/false);
-  outDir = config.outBasePath;
-
-  const std::string& packageName = getPackageName();
+runBuildCommand(
+    const std::string& outDir, const BuildConfig& config,
+    const std::string& targetName
+) {
   const Command makeCmd = getMakeCommand().addArg("-C").addArg(outDir).addArg(
-      (config.outBasePath / packageName).string()
+      (config.outBasePath / targetName).string()
   );
   Command checkUpToDateCmd = makeCmd;
   checkUpToDateCmd.addArg("--question");
 
   int exitCode = execCmd(checkUpToDateCmd);
   if (exitCode != EXIT_SUCCESS) {
-    // If packageName binary is not up-to-date, compile it.
+    // If `targetName` is not up-to-date, compile it.
     logger::info(
-        "Compiling", "{} v{} ({})", packageName, getPackageVersion().toString(),
+        "Compiling", "{} v{} ({})", targetName, getPackageVersion().toString(),
         getProjectBasePath().string()
-
     );
     exitCode = execCmd(makeCmd);
   }
+  return exitCode;
+}
+
+int
+buildImpl(std::string& outDir, const bool isDebug) {
+  const auto start = std::chrono::steady_clock::now();
+
+  const BuildConfig config = emitMakefile(isDebug, /*includeDevDeps=*/false);
+  outDir = config.outBasePath;
+
+  const std::string& packageName = getPackageName();
+  int exitCode = 0;
+  if (config.hasBinTarget()) {
+    exitCode = runBuildCommand(outDir, config, packageName);
+  }
+
+  if (config.hasLibTarget() && exitCode == 0) {
+    const std::string& libName = config.getLibName();
+    exitCode = runBuildCommand(outDir, config, libName);
+  }
 
   const auto end = std::chrono::steady_clock::now();
   const std::chrono::duration<double> elapsed = end - start;