diff --git a/pets.py b/pets.py
new file mode 100644
index 0000000..a9fd80e
--- /dev/null
+++ b/pets.py
@@ -0,0 +1,129 @@
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from typing import Iterable
+
+
+# =============================================================================
+# Pet Ingestor Interface
+# =============================================================================
+
+
+@dataclass
+class AdoptablePet:
+    """Represents a pet available for adoption."""
+
+    name: str
+    species: str  # "dog" or "cat"
+    breed: str
+    location: str
+    description: str = ""
+    adoption_url: str | None = None
+    image_url: str | None = None
+
+
+class PetSource(ABC):
+    """Interface for fetching pets from various adoption APIs."""
+
+    @property
+    @abstractmethod
+    def source_name(self) -> str:
+        """Return the name of the pet source."""
+        ...
+
+    @abstractmethod
+    def fetch_pets(self) -> Iterable[AdoptablePet]:
+        """Fetch available pets from the source."""
+        ...
+
+
+# =============================================================================
+# Social Media Poster Interface
+# =============================================================================
+
+
+@dataclass
+class Post:
+    """Represents a social media post about an adoptable pet."""
+
+    text: str
+    image_url: str | None = None
+    link: str | None = None
+    alt_text: str | None = None  # For image accessibility
+    tags: list[str] = field(default_factory=list)
+
+
+@dataclass
+class PostResult:
+    """Result of attempting to publish a post."""
+
+    success: bool
+    post_id: str | None = None
+    post_url: str | None = None
+    error_message: str | None = None
+
+
+class SocialPoster(ABC):
+    """
+    Abstract base class for social media platform implementations.
+
+    Concrete implementations should inherit from this class and implement
+    the abstract methods for their specific platform (e.g., Bluesky, Instagram).
+    """
+
+    @property
+    @abstractmethod
+    def platform_name(self) -> str:
+        """Return the name of the social media platform."""
+        ...
+
+    @abstractmethod
+    def authenticate(self) -> bool:
+        """
+        Authenticate with the platform.
+
+        Returns:
+            True if authentication was successful, False otherwise.
+        """
+        ...
+
+    @abstractmethod
+    def publish(self, post: Post) -> PostResult:
+        """
+        Publish a post to the platform.
+
+        Args:
+            post: The post to publish.
+
+        Returns:
+            PostResult indicating success/failure and relevant details.
+        """
+        ...
+
+    def is_authenticated(self) -> bool:
+        """Check if currently authenticated. Override if platform supports this."""
+        return False
+
+    def format_post(self, pet: AdoptablePet) -> Post:
+        """
+        Create a Post from an AdoptablePet.
+
+        Override this method to customize post formatting for specific platforms.
+        """
+        text = f"Meet {pet.name}! This adorable {pet.breed} {pet.species} is looking for a forever home in {pet.location}."
+        if pet.description:
+            text += f"\n\n{pet.description}"
+        if pet.adoption_url:
+            text += f"\n\nAdopt {pet.name}: {pet.adoption_url}"
+
+        return Post(
+            text=text,
+            image_url=pet.image_url,
+            link=pet.adoption_url,
+            alt_text=f"Photo of {pet.name}, a {pet.breed} {pet.species} available for adoption",
+            tags=[
+                "adoptdontshop",
+                "rescue",
+                pet.species,
+                pet.breed.lower().replace(" ", ""),
+            ],
+        )
diff --git a/requirements.txt b/requirements.txt
index e69de29..a8608b2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -0,0 +1 @@
+requests>=2.28.0
diff --git a/rescue_groups.py b/rescue_groups.py
new file mode 100644
index 0000000..b0fe183
--- /dev/null
+++ b/rescue_groups.py
@@ -0,0 +1,183 @@
+"""
+RescueGroups.org API implementation of the PetSource interface.
+
+API Documentation: https://api.rescuegroups.org/v5/public/docs
+"""
+
+import html
+import logging
+import os
+import re
+from typing import Iterator
+
+import requests
+
+from pets import AdoptablePet, PetSource
+
+logger = logging.getLogger(__name__)
+
+
+class RescueGroupsSource(PetSource):
+    """
+    Fetches adoptable pets from RescueGroups.org API.
+
+    Requires RESCUEGROUPS_API_KEY environment variable or api_key constructor arg.
+    """
+
+    BASE_URL = "https://api.rescuegroups.org/v5/public/animals/search/available"
+
+    def __init__(
+        self,
+        api_key: str | None = None,
+        postal_code: str = "02108",  # Boston
+        radius_miles: int = 50,
+        species: str = "dogs",  # "dogs" or "cats"
+        limit: int = 25,
+        location_label: str = "Boston, MA",  # For display purposes
+    ):
+        self._api_key = api_key or os.environ.get("RESCUEGROUPS_API_KEY")
+        self.postal_code = postal_code
+        self.radius_miles = radius_miles
+        self.species = species
+        self.limit = limit
+        self.location_label = location_label
+
+    @property
+    def source_name(self) -> str:
+        return f"RescueGroups ({self.species})"
+
+    def fetch_pets(self) -> Iterator[AdoptablePet]:
+        """
+        Fetch available pets from RescueGroups.org.
+
+        Yields:
+            AdoptablePet objects for each available pet.
+
+        Raises:
+            ValueError: If API key is not configured.
+            requests.HTTPError: If the API request fails.
+        """
+        if not self._api_key:
+            raise ValueError(
+                "RescueGroups API key not configured. "
+                "Set RESCUEGROUPS_API_KEY environment variable."
+            )
+
+        url = f"{self.BASE_URL}/{self.species}"
+        headers = {
+            "Content-Type": "application/vnd.api+json",
+            "Authorization": self._api_key,
+        }
+        payload = {
+            "filters": [
+                {
+                    "fieldName": "status",
+                    "operation": "equals",
+                    "criteria": "Available",
+                }
+            ],
+            "filterRadius": {
+                "miles": self.radius_miles,
+                "postalcode": self.postal_code,
+            },
+            "limit": self.limit,
+        }
+
+        logger.info(
+            f"Fetching {self.species} from RescueGroups within {self.radius_miles} miles of {self.postal_code}"
+        )
+
+        response = requests.post(url, headers=headers, json=payload, timeout=30)
+        response.raise_for_status()
+
+        data = response.json().get("data", [])
+        logger.info(f"Received {len(data)} pets from RescueGroups")
+
+        for animal in data:
+            pet = self._parse_animal(animal)
+            if pet:
+                yield pet
+
+    def _parse_animal(self, animal: dict) -> AdoptablePet | None:
+        """Parse a single animal record from the API response."""
+        try:
+            attrs = animal.get("attributes", {})
+            animal_id = animal.get("id", "")
+
+            # Extract and clean the name
+            name = self._clean_name(attrs.get("name", "Unknown"))
+
+            # Determine species from the endpoint we queried
+            species = "dog" if self.species == "dogs" else "cat"
+
+            # Get breed info
+            breed = attrs.get("breedString", attrs.get("breedPrimary", "Mixed"))
+
+            # Clean up description (use text version, not HTML)
+            description = self._clean_description(attrs.get("descriptionText", ""))
+
+            # Build adoption URL from slug
+            slug = attrs.get("slug", "")
+            adoption_url = f"https://www.rescuegroups.org/pet/{slug}" if slug else None
+
+            # Get best available image
+            image_url = self._get_image_url(attrs)
+
+            return AdoptablePet(
+                name=name,
+                species=species,
+                breed=breed,
+                location=self.location_label,
+                description=description,
+                adoption_url=adoption_url,
+                image_url=image_url,
+            )
+        except Exception as e:
+            logger.warning(f"Failed to parse animal {animal.get('id', 'unknown')}: {e}")
+            return None
+
+    def _clean_name(self, name: str) -> str:
+        """
+        Clean up pet name by removing promotional text.
+
+        Examples:
+            "Doli ***Home for the Holidays 1/2 price!" -> "Doli"
+            "Kathy" -> "Kathy"
+        """
+        # Remove common promotional suffixes
+        # Split on common delimiters and take the first part
+        cleaned = re.split(r"\s*[\*\-\|]+\s*", name)[0]
+        return cleaned.strip()
+
+    def _clean_description(self, description: str) -> str:
+        """Clean up description text."""
+        if not description:
+            return ""
+
+        # Decode HTML entities
+        text = html.unescape(description)
+
+        # Remove   and normalize whitespace
+        text = text.replace(" ", " ")
+        text = re.sub(r"\s+", " ", text)
+
+        # Remove promotional headers
+        text = re.sub(
+            r"\*\*Home for the Holidays.*?\*\*", "", text, flags=re.IGNORECASE
+        )
+
+        # Trim to reasonable length for social posts
+        text = text.strip()
+        if len(text) > 500:
+            text = text[:497] + "..."
+
+        return text
+
+    def _get_image_url(self, attrs: dict) -> str | None:
+        """Get the best available image URL."""
+        # The thumbnail URL can be modified to get a larger image
+        thumbnail = attrs.get("pictureThumbnailUrl")
+        if thumbnail:
+            # Remove width parameter to get full-size image
+            return re.sub(r"\?width=\d+", "", thumbnail)
+        return None