diff --git a/README.md b/README.md
index 68964a1..4db152b 100644
--- a/README.md
+++ b/README.md
@@ -30,8 +30,11 @@ merge2pdf output.pdf input1.pdf~1 input2.pdf input3.pdf~2,3,4
 # Merge multiple Images
 merge2pdf output.pdf image1.jpg image2.jpg path/to/other.png ...
 
-# Mixing up PDF, PDF Pages and Images
-merge2pdf output.pdf doc1.pdf~1,2 image1.jpg image2.png path/to/other.pdf ...
+# Merge all Images/PDFs of one or multiple directory
+merge2pdf output.pdf path/to/a/dir path/to/another ...
+
+# Mixing up PDF, PDF Pages, Images and directories
+merge2pdf output.pdf doc1.pdf~1,2 image1.jpg path/to/dir path/to/other.pdf ...
 ```
 
 ### Fine tuning Image pages
@@ -65,17 +68,23 @@ To see details of options,
 ```bash
 merge2pdf -h
 ```
+### Notes
+
+- `--size`, `--margin`, `--scale-width`, `--scale-height` will only effect images. 
+- PDF pages will inherit size and margin of source PDF
+- _Some_ `.tiff` files (e,g, compression level 4) may not work properly
+- Directory inputs will be searched for image/PDF files on first level only. Subdirectories will be skipped.
 
 ### Roadmap
 
 ✅ Merge multiple PDFs without loosing quality  
 ✅ Merge multiple PDFs with **selective pages**  
 ✅ Adding Images  
-✅ Mixing up Images and PDFs  
-◻️ Merge all (Image and PDF) files from directory  
+✅ Mixing up Images and PDFs    
+✅️ Merge all (Image and PDF) files from directory  
 ✅ Option to Resize Images to reduce filesize  
 ◻️ Option to Greyscale Images to reduce filesize  
-◻️ Option to set files and pages as JSON config to make usages from other app more convenient  
+◻️ Option to set files and pages as JSON config to make usages from other app more convenient    
 
 ### Contribute
 
diff --git a/dir.go b/dir.go
new file mode 100644
index 0000000..c3464e0
--- /dev/null
+++ b/dir.go
@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/unidoc/unidoc/pdf/creator"
+)
+
+type DirSource struct {
+	path  string
+	files []Mergeable
+}
+
+func (s DirSource) MergeTo(c *creator.Creator) error {
+	debugInfo(fmt.Sprintf("Adding Directory: %s", s.path))
+	var err error
+
+	for _, mergeableFile := range s.files {
+		err = mergeableFile.MergeTo(c)
+		if err != nil {
+			break
+		}
+	}
+
+	return err
+}
+
+func (s *DirSource) scanMergeables() {
+	filesInDir, _ := ioutil.ReadDir(s.path)
+
+	for _, file := range filesInDir {
+		if file.IsDir() {
+			continue
+		}
+
+		s.files = append(s.files, getMergeableFile(filepath.Join(s.path, file.Name()), []int{}))
+	}
+}
diff --git a/main.go b/main.go
index ca9949c..4762666 100644
--- a/main.go
+++ b/main.go
@@ -31,8 +31,8 @@ func init() {
 
 	flag.Usage = func() {
 		fmt.Println("merge2pdf [options...] <output_file> <input_file> [<input_file>...]")
-		fmt.Println("<output_file> should be a PDF file and <input_file> can be PDF or image files. PDF files can have specific page numbers to merge.")
-		fmt.Println("Example: merge2pdf output.pdf input1.pdf input_pages.pdf~1,2,3 input3.jpg /path/to/input.png ...")
+		fmt.Println("<output_file> should be a PDF file and <input_file> can be PDF, image or directory. PDF files can have specific page numbers to merge.")
+		fmt.Println("Example: merge2pdf output.pdf input1.pdf input_pages.pdf~1,2,3 input3.jpg /path/to/dir ...")
 		flag.PrintDefaults()
 	}
 }
diff --git a/source.go b/source.go
index 09fbbcd..c794388 100644
--- a/source.go
+++ b/source.go
@@ -12,7 +12,7 @@ import (
 	"github.com/unidoc/unidoc/pdf/creator"
 )
 
-type mergable interface {
+type Mergeable interface {
 	MergeTo(c *creator.Creator) error
 }
 
@@ -22,13 +22,42 @@ type source struct {
 }
 
 // Initiate new source file from input argument
-func NewSource(input string) mergable {
+func NewSource(input string) Mergeable {
 	fileInputParts := strings.Split(input, "~")
 
 	path := fileInputParts[0]
-	f, err := os.Open(fileInputParts[0])
+	var inputSource Mergeable
+
+	info, err := os.Stat(path)
 	if err != nil {
-		log.Fatal("Cannot read source file:", fileInputParts[0])
+		log.Fatal("Error:", err.Error())
+	}
+
+	switch mode := info.Mode(); {
+	case mode.IsDir():
+		inputSource = getMergeableDir(path)
+	case mode.IsRegular():
+		pages := []int{}
+		if len(fileInputParts) > 1 {
+			pages = parsePageNums(fileInputParts[1])
+		}
+		inputSource = getMergeableFile(path, pages)
+	}
+
+	return inputSource
+}
+
+func getMergeableDir(path string) Mergeable {
+	dir := DirSource{path: path}
+	dir.scanMergeables()
+
+	return dir
+}
+
+func getMergeableFile(path string, pages []int) Mergeable {
+	f, err := os.Open(path)
+	if err != nil {
+		log.Fatal("Cannot read source file:", path)
 	}
 
 	defer f.Close()
@@ -36,7 +65,7 @@ func NewSource(input string) mergable {
 	ext := filepath.Ext(f.Name())
 	mime, err := getMimeType(f)
 	if err != nil {
-		log.Fatal("Error in getting mime type of file:", fileInputParts[0])
+		log.Fatal("Error in getting mime type of file:", path)
 	}
 
 	sourceType, err := getFileType(mime, ext)
@@ -44,14 +73,9 @@ func NewSource(input string) mergable {
 		log.Fatal("Error : %s (%s)", err.Error(), path)
 	}
 
-	pages := []int{}
-	if len(fileInputParts) > 1 {
-		pages = parsePageNums(fileInputParts[1])
-	}
-
 	source := source{path, sourceType, mime, ext, pages}
 
-	var m mergable
+	var m Mergeable
 	switch sourceType {
 	case "image":
 		m = ImgSource{source}
@@ -77,7 +101,7 @@ func getFileType(mime, ext string) (string, error) {
 		return "image", nil
 	}
 
-	return "error", errors.New("Could not detect file type.")
+	return "error", errors.New("File type not acceptable. ")
 }
 
 func parsePageNums(pagesInput string) []int {